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NOTE:  Items highlighted in RED are defined elsewhere in this Glossary, while items highlighted in BLUE are site links for further information.


R: A programming language used primarily by data scientists to handle statistics and data visualization.

RAC: Remote Access Card, usually a PCI card used to provide over-IP access and therefore control to remote and server computers, sometimes for malicious purposes.

RACE CONDITION: A condition which can result if concurrent transactions create a result which is innacurate because the data is not locked out as each sequential transaction is logged (known as Mutual Exclusion or “Mutex”).  Used quite often in banking transactions.  The good news is banks will usually sort and credit the day’s deposits first (known as a “semaphore”), then deduct payments (or the next level of priorities, such as ATM withdrawals) thereafter.

RACEWAY: An enclosed conduit that forms a physical pathway for electrical, telephone, computer and other cabling.  Useful because it protects the cables from heat, humidity, breakage, corrosion and water.  Depending on the application, cable may be metal, plastic or PVC, flat or round, either inside or over interior walls or ceilings.  If there is the possibility of electromagnetic interference (“EMI”) grounded metal raceway should be used.  Plastic conduit is mainly used for cable not requiring electrical grounding, or for cables such as coaxial, which contain their own RF shielding.


RACKMOUNT or RACK: An open or closed cabinet (with door) into which are mounted computer components, usually in larger installations.  Cabinets and racks are usually measured in RMUs, where each RMU or U is equivalent to 1.75 inches.  See also: “U

computer rack

RAD:  Rapid Application Development.  A programming process where a form representing final output, often with “dumb” control buttons is created, to let the end user see how it will look. James Martin was one of the main developers.

RADAR:  An acronym for Radio Detection And Ranging. Based on principles described by Heinrich Hertz in 1886. as expanded upon by many scientistsfrom many countries thereafter, radar is a method of finding the position of an object by bouncing a radio wave off of it and then analyzing the reflected wave to determine its position, range, altitude, direction and speed.  Used frequently by police to detect speeding and the military to detect and locate enemy vehicles.

RADIANT THINKING: See, Linear Thinking. The opposite of Linear Thinking.  Akin to brainstorming.

RADICAL: An mnemonic acronym created by Karen Christenson, a library media specialist, to evaluate information found on line.  It stands for:  Relevancy, Appropriateness, Detail, Currency, Authority and Bias.  See for more information.

Radio ShackRADIO SHACK: An iconic electronics supplier headquartered in Boston, by 2015 pretty much on life support, which is why I’m writing this like an obituary.  Founded in 1921 by two brothers from London, Theodore and Milton Deutschmann, it was named for the compartment on ships where the wireless electronics were stored.  The core mission of the company was originally ham radio enthusiasts.  Through the years, the company shifted its focus to CB Radios in the ‘70s, then introduced the TRS-80 personal computer in 1977 (through 1993; the first computer to use the Microsoft O/S, even though it used a tape recorder for storage, since the hard drive hadn’t been invented yet for PCs), then it’s own “big box” stores (like Incredible Universe, Computer City and Famous Brand Electronics) in the late 1990s, before moving into cell phones in the 2000s. By 1962, however, the company was losing so much money that it’s main creditor, First National Bank of Boston, sold it for ten cents on the dollar to a Texas businessman named Charles Tandy in 1963, who then successfully operated the company for quite some time.  Hence the name change to Tandy Radio Shack (“TRS,” as in the TRS-80 computer).  But, in each instance of its reinvention, RS was either too late, didn’t embrace its new business, didn’t train its employees well or didn’t evolve as others surpassed them.   It’s sad, because RS was the one retail chain that started the now-popular “maker movement,” courting the electronics DIYers now embraced by Raspberry Pi and Arduino, personal drones, Maker Faire and other electronics tinkering venues. When the company started, most of the counter employees were valuable sources of information about the parts the company sold; no longer is this the case.  It’s been said that Steve Jobs and Steve Wozniak, Apple’s founders used diodes and transistors they purchased at Radio Shack to build their “blue box,” a device that was used to trick the tone phone system to make free long-distance calls.  And almost every kid I knew went to Radio Shack to get parts for their science fair projects. There were other companies, like Lafayette Radio Electronics, Allied Radio and even most of Heathkit, but none of them had retail operations like Radio Shack.  Most were catalog companies, with few or no retail stores.  Radio Shack started with a successful catalog, but discontinued it. [Most of these other DIY companies aren’t around any more, either.  But you can always order electronic parts over the Internet, even from China, if you want to.  But the support isn’t there.  ]

RADIX COMPLEMENT: See, Twos Complement.

RADIUS: Remote Authorization Dial-In User Service.  The standard protocol for authentication servers (“AAA”) developed by Lucent, which uses a challenge/response method for authentication by a computer server, access point or the like.  Used in the more recent encryption schemes.

RAID:  Stands for “Redundant Array of Independent Disks”.  This involves the storage of data on a set of several hard disk drives (the “array”), so that if one of the hard drives on a computer system fails, others in the RAID array may immediately replace the bad drive.  There are at this time at least eleven types of RAID, designated RAID-0 through 7, 10, 53 and 0+1.  RAID arrays are generally categorized according to whether they are “mirrored” (they create exact clones of the drive in question) or “striped” (only parts of the hard drive to be duplicated are put on each of the RAID drives).  The former is slower but complete (a “rebuild”), the latter faster but will not allow a complete restore.  But remember that, while a mirrored drive will replace a hardware failure on an active hard drive, it will also copy any viruses as well.  There are also two types of caching:  “Write-back, which is faster, signals that a data transfer is complete when the controller cache has received all data in the transaction.  Using “write-through” caching, which is more secure, the controller signals that a data transfer is complete when the disk subsystem has received all the data.  However, there are much less expensive tools for backup these says, due to the low cost of hard drives.  RAID should not be confused with DISK SPANNING, which combines multiple drives, but displays them in the operating system as a single drive.  (See JBOD.) Four 20Gb drives in RAID would show as four 20gb drives; if they were spanned, they would show as one 80Gb drive.  Spanning provides no data protection, only a convenient way to display multiple drives.  For a truly excellent graphic showing the operation of the various levels of RAID, click HERE.

RAINBOW (PRECOMPUTING) TABLE: Used to break encryption.  See Hellman.

RAINDROP: A project that Mozilla Labs characterized as “an open experiment in messaging on the web”.  Introduced on 10/22/09, Raindrop used the most common browsers to sift conversations from various sources such as e-mail, Twitter and RSS feeds, pulling out the important parts, then having them rise to the top of the list, effectively “personalizing” your inbox.  Apparently, it never got past the prototype stage and never had a stable release.

RAM:  Random Access Memory”.  This is the memory used to run your computer’s operating system and any programs

This memory is to be distinguished from the memory on your hard disk drive in three important respects:  First, the RAM is completely emptied every time the computer is turned off.  Second, the RAM represents only the amount of memory allowed in the computer to work on various programs and files, while the hard drive includes all of the systems, files, folders and programs that are saved on your computer.  Third, the RAM is generally on separate chips inserted onto the computer’s main circuit board.  The hard drive is like a “file cabinet” that permanently saves every line of code on your computer (including the operating system), while the RAM is more like the desk space you have available to spread out the files you take out of that file cabinet to work on.  And there are rules you have to follow:  You must use the pages of that file side-by-side and, when you run out of desk space, the rest of the pages fall off the desk and are not useable.  You can’t just put them on the floor or your knee to read the pages. That is, you have to have a big enough “desk” (i.e. sufficient RAM), or you must add more to your “desk” (i.e. increase the RAM).

Distinguish this type of temporary memory from CACHE (pronounced “cash”) which is a temporary place for storage of data and instructions between a storage device (a hard disk, for example) and the processor (chip). 

RAM comes in various types and capacities, including DRAM,SIMM, DIMM, SRAM, SDRAM and DDR, DDR-2 and DDR-3 RAM.  Click HERE for a detailed discussion and photos of the various types of RAM and learn how RAM works.

RANSOMWARE: Click HERE for explanation.

RARE EARTH METALS:  Seventeen chemical elements at the very end of the periodic table  (elements 57 - 71; with names like praseodymium and yttrium) found in the earth’s crust which are necessary for the manufacture of such important items as laptops, cell phones, MP3 players, electric cars (which each take some 25 pounds), wind turbines, smart bombs, F-35 fighter jets, Tomahawk cruise missiles, MRI machines, super magnets (in virtually every cell phone and MRIs), electronics and wind turbines (neodymium), photovoltaic cells, glass polishing (Cerium), hybrid car batteries (Lanthanum) and the like.  They’re actually not so rare, just extremely difficult, therefore expensive, to extract.  Until the 1990s, the U.S. was the dominant producer of these metals and China produced almost none.  Then things changed:  The virtual monopoly of Denver-based Molycorp ended with the bankruptcy of the company, closing the mines, primarily due to the environmental hazards caused by the acids and other chemicals required to mine the materials.  As the direct result, in the early 2000s, China was able to step in and quickly assumed a majority position, producing about 97% of the world’s rare earth metals. However, when China upped the price of the metals by 500% or more, some industries found workarounds (e.g. recycling Cesium or developing items that don’t require rare earth metals or instead obtaining them from Australia or Malaysia).  By 2010, however, Molycorp reopened its Mountain Pass Mine in California, causing an immediate drop in prices of the metals (between 80% and 90%), even as China still controlled some 70% of the market at that point.  Molycorp still hasn’t turned a profit and there are additional environmental issues.

RASPBERRY Pi:  Click HERE for more...

RASTER GRAPHIC:  See, Vector Graphic.  Also sometimes called a “bitmap graphic.”

RAT:  Remote Administration Tool.  Any tool that allows a computer to be controlled from a remote location.  A RAT may be paid or free, also run with permission or without permission (malware).

RATING:  See, Score

RATIONAL NUMBER:  Any number (“ratio”) that can be made by dividing one integer by another,  E.g. 2 is a rational number (“2/1”), but pi (3.1416...) isn’t, it’s an irrational number.

RAW:  (1)  Any Internet protocol other than TCP or UDP.  It’s a term, not an acronym.   Because it allows programs to send and receive packets directly without relying on TCP or UDP, without verification and correction it is mainly used as the default protocol for print devices and diagnostics.  See also, ICMP. (2) When applied to data, any data that has been collected but not filtered or analyzed in any fashion.  (3) When applied to things like live streaming video (e.g. on Facebook), it similarly means that it is unfiltered, live and unedited.  (Not always a good thing, as people have streamed their own suicides or crimes, but that’s another issue entirely.)

RAY TRACING:  A technique for creating high-resolution images.  It uses a library known as Embree, made available for free from Intel.  The problem is that ray tracing uses considerable computing power such as parallel resources.

RC:  A designation for Microsoft software, meaning “Release Candidate.”  This is the stage of development between beta and final release, at which the program is pretty much bug-free and ready-to-go.

RDBMS:  Relational Database Management System.  This is a method of structuring the storage of data into collections of tables that can be logically associated with each other by certain shared attributes (name, value, etc.).  RDBMS such as Microsoft SQL Server go one step further than a simple search by searching through data by considering each attribute as a “set” and defining where several sets “overlap”.  [Think of a series of circles, each a database listing, which intersect at a certain point to reveal data common to all.] Also, by separating the log from the database file, SQL Server makes the search faster and preserves the database from losses due to crashing.  See also, Database.

RDC:  See: Remote Desktop Connection.  A Windows utility which allows you to connect to your computer remotely, through the use of IP addresses.

RDF:  Stands for “Resource Description Framework”.   RDF is a language for representing information about resources in the WWW.  used as a base by XML web pages to support meta data across many internet applications, making them more human readable and machine understandable.

RDP:  Stands for “Remote Desktop Protocol”.  This is a protocol designed for secure communications between computers in networks using Microsoft Windows Terminal Services.  It provides a secure remote connection into a another network computer for purposes of diagnosis, data transfer, etc.

REAL TIME:  Instantly.  When you chat in a chat room or with tech support, you communicate right then.  This is as opposed to delayed communication, such as posting in a forum or discussion group, where the post is answered later.

REBOOT:  To restart.  See boot for more.  The process of re-initializing the operating system software on a computer. WARM reboot means to restart the system software only, without powering down the computer.  COLD reboot means to shut down the power on the system, let it stand for up to 30 seconds to dissipate the static electrical power on the hardware boards, then restart the system hardware & software.

RECIMG:  The Win 8 tool for preserving the Windows desktop and create a custom system image.

RECORD:  We could be talking about LPs, those large, black plastic disks that held music.  But we’re not.  Instead, a record is a single file in a database program.  Every record has exactly the same information in the same place, called “fields,” so that they can be sorted efficiently.  Think of a box of recipes:  Each 3 x 5 card has the same information fields (e.g. date, category (desert, appetizer), ingredients, instructions (mixing, cooking times), servings and source.) 

rectifier symbolRECTIFIER:  A component found on PCBs and semiconrectifier photoductors, for the purpose of converting electrical current from AC to DC, by allowing it to flow in one direction only (not back again) like a diode.

RECURSIVE:   As in “we traced this URL with a recursive spider” or “GNU” is a recursive acronym”.  In simple terms it’s “something which builds upon itself”.  To go further, though, it is almost impossible to define without creating further confusion.  In mathematics and computer science, recursion is defined as “creating a class of objects (or methods) by defining a very few simple base cases of the class (or method), and then defining some rules to break down complex cases into simpler cases”.  Got that?  The “simple” definition of recursive is that it is a method of defining functions in which the function being defined is applied within its own definition.  [See, that was absolutely no help and reminds me why I had so much trouble with math in high school.] 

So, let’s try by example:  Base case:  One’s parents are one’s ancestors.  Recursion “steps”:  Step 1: The parents of one’s ancestors are also one’s ancestors.  Step 2: So were their parents.  Step 3: And their parents parents.  If you were unlucky enough to have taken the “new math” in high school, you can think of recursion as a “subset” to a “set”.  One thing (the “subset”) fits within, and is defined by, another (the “set”) above it.  Or, in plain English, a recursive definition will define newer objects in terms of previously defined objects of a class.  Further, the recursion construct must be limited by the number of layers or steps that one desires from the base case (in the above example, say, go back no further than great-great-grandparents), otherwise an endless “loop” would be created.  So, a recursive spider would be a software bot that would search the Internet for a class of results that would be within a certain number of “steps” (or for you movie buffs, “degrees of separation”) from a base definition while including that definition and the rules for its application.  You can best understand this by graphic exampleDrostes:

recursion land-0-lakes The “Droste Effect” is shown in the Droste advertisement, where a nun carries a tray of Droste cocoa, on which is a picture of a nun who is, in turn, carrying a tray of cocoa, the box in turn showing the same thing, and so on.  Same for the Land-O-Lakes butter package (left), recursively showing an American Indian holding another package, which in turn shows another Indian on the package, etc.Escher's_Relativity The limits, in those cases, are those pictures you can see.

Painter recursiveLet’s try another: The photo at left showing a painter painting a picture of a painter painting a picture, on and on. Or one of the M.C. Escher drawings like “Relativity,” (at right) of the famous never-ending stairway which defies gravity.


broccoliFinally, think about the “fractal” nature of cematryoshka dollsrtain vegetables like broccoli; every chunk you tear off will look (pretty much, but not exactly) like the original whole, just smaller. Or the Russian Matryoshka dolls (right).  By now, you’ve noticed that, each time you reduce the whole (i.e. the “problem”), it gets smaller.

Finally, let’s pick an even easier example using language:  A “recursive acronym” is an abbreviation that refers to itself for it’s definition.  Example:  GNU mean’s “GNU’s Not Unix”; CAVE means “Cave Automated Virtual Environment”; Cygnus means “Cygnus, Your GNU Support”; get it?  Like I said, it “builds upon itself”.

So, we’ve seen the use of recursion in art, language, math and nature.  Now, let’s apply this to computer programming:  Recursion is a process in which a function (the subset) calls upon itself (the set) as a subroutine.  This allows the function to be repeated several times without “reinventing the wheel” each time, since it “calls itself”  during each execution.  And each time, the set becomes smaller and more well defined.  Recursion solves problems, particularly fractal ones, by a “divide and conquer” mentality, that is, by solving smaller versions or parts of the problem first.  Functions that incorporate recursion are therefore called recursive functions.  These functions make efficient but not necessarily fast programming tools, because they use less code.

READYBOOST:  A function in Windows Vista that allows USB drives to be used as auxiliary random access memory.   It is used in conjunction the Super Fetch technology in Microsoft’s Windows Vista and later operating systems that pre-loads files in anticipation of the user’s requirements.

RECOTS:  An acronym for Ready Commercial Off the Shelf, as opposed to custom ordered parts and components for assembling electronics.

RECYCLE BIN:  A Windows folder, represented by a desktop shortcut icon, which holds deleted files and allows them to be restored from the location they originally resided.  The idea of restoring an erased file is actually a really big deal.  Until this feature was created, whatever you deleted, didn’t save or erased was gone forever.  All deleted files, of course, don’t automatically go to the Recycle Bin, nor does it contain files from removable media like flash drives.  The original waste container for deleted files was created by Apple for the Lisa in 1982, and it was called the Wastebasket.  It was carried over to the Macintosh as the Trash folder.  The Trash icon was one of the few copyright protected items that the courts upheld in Apple’s favor, so other manufacturers were forced to use metaphores like Recycle Bin, Smart Eraser or Shredder.  Microsoft implemented the concept of the trash bin in MS-DOS 6 (as the Delete Sentry) and the Recycle Bin with the restore feature was created in Windows 95 and, depending on the version, the files are stored in different locations.

Reddiut LogoREDDIT:  An Internet site which calls itself “The Front Page of the Internet”; it has been ranked as the 33rd most visited Internet site by Alexa..  It is a message board where users create and run their own forums on any topic they desire, and then other users can “upvote” or “downvote” the content.  The name is a portmanteau of “read/edit” and “read it,” i.e. “I read it on Reddit”.  Click HERE for a tutorial which explains the site.   Reddit, which Quantcast claims in 2012 has over 19 million users a month, was founded by Steve Huffman and Alexis Ohanian, graduates of UVA, and was acquired by Advance Publications in September 2011 after it in turn acquired Conde Nast, which bought Reddit in 2006. Aaron Swartz is commonly credited as being a co-founder of Reddit, but he actually became a partner only after it’s merger with his company, Infogami in 2005 and he left in 2996 after the Conde Nast merger because he didn’t like the work environment.   It’s still operated as an independent entity, though.  A type of site first popularized by Digg (in fact, after a disastrous version 4, so many users fled Digg for Reddit that the Reddit site temporarily added a shovel icon to welcome the new users.)  Users are known as “redditors,” another portmanteau of “reddit” and “editor”.   At first the site appears complicated, but once you get the hang of the community (which is similar to the old “bulletin boards”), its comments, the subreddit categories, multi-reddits and the lingo (e.g. OP = Original Poster; TIL = Today I learned; DAE = Does Anyone Else; IAmA = I am a; AMA = Ask Me Anything; TL;DR = Too Long, Didn’t Read; FTFY = Fixed That For You), it is addictive.  Each category is administered by a “Mod” (moderator).  Reddit, along with its friends Twitter, Facebook and others is widelSnoo Longboardingy credited with rallying support in 2012 to halt the progression of anti-piracy bills in Congress until further review and changes.  The alien in the logo is named “Snoo” and jokes on the site that he also “does birthday parties”. The original name for Reddit was “” as in “what’s new,” hence the mascot’s name.   He was created as a doodle by “/u/kn0thing” while at UVa, has undergone several revisions (just like Duke, the Java mascot) and even invites users to create their own versions.  See also, Aaron Swartz. And the phenomenon known as the “Reddit Hug” or the “SlashDot effect,” which describes what happens when sites like Reddit create such a high influx of hits to a smaller website which it references that they can even crash that site’s servers.  In 2014, Reddit opened its own crowdfunding site. 

There was a brief revolt in July, 2015 when Victoria Taylor, who joined Reddit in 2013 to be its first director of communications, later director of talent, was dismissed by the company for some unspecified reason (our moderator policies have to be changed”).  Her key area was the “AMA” part of the site, short for “Ask Me Anything,” which will continue without Taylor, but with a new position known as “Moderator Advocate”.   For about a week, the other “moderators” of the site blocked major portions of the site from the general public in protest of this beloved director, and some 200,000 users petitioned Reddit for the ouster of Ellen Pau, its CEO, who stepped down a week later. 

RED HAT:  Refers to a distribution of Linux that is freely downloadable off the Internet.  Red Hat was one of the first versions of Linux to be made readily available and made Linux a mainstream product.

RED ROOM:  See, Deep Web.

RED TEAM:  The name usually given to internal corporate pen testing teams.  See, Pen Testing.

REED-SOLOMON:  See Checksum, encryption.  An error correcting code written in 1960 by Irving S. Reed and Gustave Solomon of MIT which detects multiple random symbol errors primarily for use in consumer electronics like CD/DVDs, and was also used in the NASA Voyager program.

RE-FLASH:  This is the process of updating information stored on a chip with replacement instructions.  For example, when you re-flash the BIOS or the NIC card, you completely erase the information on the chip and replace it with completely new instructions.  It is called “flashing” or “re-flashing” because the code is stored on a programmable chip in what is known as “flash memory”.  The process is done either through the built-in functionality of the program already on the chip or another DOS or Windows based program.  It’s not a good idea to flash the BIOS unless it is absolutely necessary because if there is a problem or a power outage, it may brick the computer.  Some types of older NIC cards automatically reflash each time they’re booted.  See PXE-ROM.

REFRESH RATE:  Refers to the number of times per second that display hardware (like a computer screen) draws the displayed data, usually measured in Hz (cycles per second).  For example, a 60Hz refresh rate indicates that the screen is redrawn 60 times per second.  Typical monitor refresh rates are 60, 66, 75 and 85Hz.  Sometimes called the “vertical refresh rate” or, for CRTs, the “vertical scan rate”.  Increasing the rate decreases “flickering” on a CRT monitor, reducing eye strain and provides a clearer image; but a refresh rate too high may damage the monitor.   LCD monitors are usually manufactured with a set refresh rate well above the flicker point; LCD monitors produce less flicker than CRTs because the pixels on a LCD screen stay lit longer before they noticeably fade.  For more about monitors and screens, click HERE.

ReFS:  Resilient File System.  A new type of local file system used with later Windows versions like Windows 8.  It has greater data integrity than NTFS so that critical data is more protected from errors that would have caused data loss or errors with previous Windows file systems.  It was first introduced with Windows Server 2012 with the intention of enhancing data integrity for business systems.  Check Disk cannot be used with ReFS because of its construction and, anyway, it runs essentially the same thing each time the computer starts up.  For a discussion comparing the features of NTFS vs. Refs, click HERE.

REGISTER:  In computer architecture, the processor register is a small amount of “special-purposememory storage available on the CPU chip for the purpose of moving data in and out of the computer’s main memory (like the hard drive) so that operations can be performed quickly on that data.  Basically, it’s where computers store the data it uses to compute.  It is used, particularly for operations such as arithmetic processing, because it provides faster access and speed for operations, after which the computer can then save the processed data back again onto slower memory such as the hard drive. Most microprocessors have 14 registers in them, the most common of which are the ones for instruction, addresses and input/output (“I/O”) registers.  I couldn’t find any explanation about why the term “register” is used, so I’ll stick with my feeling - it’s like a cash register, where you put money in at the beginning of the day, then take it out at the end. It’s temporary, just like the data in the processor register.  That’s my definition and I’m sticking with it.  See also Chips.  While the register architecture is by far the most common computer architecture, the ”stack” machine is another architecture that is common. In that case, a computer uses a “pushdown stack” as opposed to individual machine registers using something known as a “reverse Polish notation instruction set” to evalate program instructions.  Instead of explicitly naming specific registers for operations, the stack machine uses only the top two registers in the stack, and pushes them down as they operate.

Registry symbolREGISTRY:  The system registry is probably the single most important part of Windows.  It is a system-defined database used by the Windows operating system to store configuration, such as the installation of programs, hardware and the like.  Only professionals should edit the registry, because even a slight slip of the keyboard can render your computer completely useless.  For more information about the system registry, click HERE.

REJ:  See ACK.

REM:  Shorthand for “remark”.  This is used in DOS and BASIC to introduce a comment in a program line and separate it from a command.  Example:  “10 REM This BASIC program shows the use of the PRINT statement”

REMOTE DESKTOP CONNECTION (RDC):  A feature in Windows that allows a computer, through an ActiveX control and a Web-based process, to remotely access another computer.  Useful if you want to remotely access your office computer, for example.  There are other, non-Windows operating system programs that do the same thing:  LogMeIn, TeamViewer, VNC, Splashtop, Pulseway, Citrix, Remote Utilities, Ammyy Admin, AeroAdmin, Fimass and AnyDesk among hundreds of others.  NOTE:  If you are having any problems with someone possibly accessing your computer without your permission, check for and remove any of these programs if you did not give them permission to be installed (for example for service assistance).  If it was for service assistance, be sure to remove the program after the service is complete.  See also, VPNs.

RENDERING:  (1) In computer graphics, the process of generating an image using software. It’s both a verb and a noun, as the end result (usually a digital image or raster graphics image file) can be called a rendering. (2) Respecting web pages, it is the process of communicating with the networking layer of a browser to translate the HTML code from a page on a remote server and displaying it on the user’s screen.  Rendering can be done “client-side”  or “server-side”.  Client-side is most common, doing the rendering almost entirely on the user’s computer, while server-side rendering performs this task on the server before it is transmitted to the user’s browser.  Client side is most common, but server-side usually loads faster.

REPEATER:  An item of computer hardware that boosts the standard strength of a signal on the network so that it can travel beyond its limit.  For example, on an ethernet network, a signal can travel about 100 meters or 328 feet without being boosted by a repeater, further if it is.  See also hubs, bridges.

REPOSITORY:  A catalog or list of packages available for downloading from a single location.  A term used in Linux and elsewhere.  See also Git.

Resistor symbolRESISTOR:  A device found on integrated circuit boards which resists the flow of electrical current, causing a drop in voltage across the device.  Resistance is measured in Ohms, the value of which is either printed or defined by colored bands around the device (0 through 9; e.g. red is 2).  A resistor could reduce the voltage for a circuit board, or slow down a motor, or prevent burning out a device.  See Thermistor.

RESOLUTION:  Generally, the clarity of a picture, as defined by the number of pixels (individual points of color) displayed on a screen.  The higher the number, the greater the resolution.  This measure was relatively simple with the old CRT monitors, became slightly more difficult with LCD/LEDs and doesn’t really apply to HDTVs, except for the general rule that greater resolution = greater clarity.  But, with digital cameras, increased pixels are not the main determinant of photo quality, it’s the processor itself.  Click HERE for more.

REST:  Representational State Transfer.  A software protocol that allows Web applications to quickly access and manipulate data through simple http calls.

RESTORE:  The process of copying backup files or drives back to the original computer so that no data is lost.  For more, click HERE.

RESTORE PREVIOUS VERSION:  A feature in Windows Vista and Windows 7 that allows the user to restore previous versions of every data file and folder on the computer, much like Restore Point allows the system to be restored to an earlier date point.

RESOURCES:  A term which references all of both hardware and software (including virtual) components available for use by a computer system.  As more and more components are used at the same time, their limited availability becomes exhausted.  When this happens, the program (including the O/S)  and/or hardware may become “deadlocked” and freeze as threads or processes (access to which are controlled by something known as semaphores) may attempt to allocate resources already in use. One measure of system resources used can be seen in the Windows Task Manager (“Ctrl+Alt+Del”), where the Performance tab will show you, on a scale between 0 and 100%, the amount of total system resources and RAM currently being consumed by the system, an indicator of the power left in the system to accommodate additional hardware or software and sometimes that a virus or malware is consuming too much power communicating remotely with its initiator.

RESTRICTED MODE:  See, Administrative Mode.

RETINA DISPLAY:  A marketing term developed by Apple to refer to its devices that have an ultra-high pixel density (more than 300 pixels per inch) such that the display is so clear and crisp that a human is unable to discern the individual pixels at a normal viewing distance.  It was introduced in 2011 with the iPhone 4S and has been included on versions of the iPad (2012) and newer MacBook Pros (2012).

RF:  Radio Frequency. Refers to devices (such as RFID’s or Zigby) that use radio waves to communicate.

RFI:  Radio Frequency Interference.  Signals which are created (in the normal course of operation) by the electromagnetic radiation that is emitted by electrical currents carrying rapidly changing signals, also florescent lighting.  This type of interference is easily filtered out.  See, Faraday Cage.

RFID:  This stands for “Radio Frequency Identification Device”.  An RFID is a chip or a length of encoded “tape” that if affixed to an item so that it’s location can be traced.  You may notice that some stores have these strips attached to them, and that they have to be “deactivated” before you leave the store or else an alarm will sound.  Aside from security, these chips often have a dual purpose.  Prior to arriving at the store, these chips on products or on the shipping or warehouse storage boxes or palettes help identify where these products are and how many of them there are.  Wal-Mart was one of the first to introduce the extensive use of RFID in the mid-1990s.  See also NFC.

RGB:  Standard video format for computer monitors, because most video devices such as digital cameras, game machines, etc., produce output in RGB format.  The RGB color model is one in which the primary colors Red, Green and Blue light are added together in various ways to reproduce a broad array of colors.  Output for modern televisions, however, looks better in S-Video format.  Sometimes “Y” is added for yellow, such monitors called RGBY.  For more about monitors and screens, click HERE.

RIA:  Rich Internet Application. A type of web application that can run independently of browsers, can run on any operating system and in many ways works like a traditional desktop application.  (e.g. Flash, Shockwave, Java; Adobe AIR, Curl, Microsoft Silverlight, Mozilla Prism).

RIBBON:  A user interface first introduced by Microsoft in Office 2007 (and expanded to other Microsoft programs and versions) which replaced the old drop-down menus with a large top horizontal tool bar filled with graphic representations of control elements which are grouped by their functionality, some of which only appear when certain objects are selected.  See, contextual tabs.  The Word toolbar is shown below.  Each tab on the top menu bar activates a specific ribbon bar below with its own icons as well as an arrow at the lower right which provides even more selections:


RICH:  As in “rich internet format” or “rich text format”.  This refers to the addition of formatting features beyond basic or standard (e.g. text) files but not as much as full program features.

RICH Internet Format (“RIF”):  Also sometimes Installable Internet Application.  This refers to a web application designed to emulate desktop application software which normally doesn’t require software installation.

RICH TEXT FORMAT (“RTF”):  A text file format specification developed by Microsoft and commonly used between 1987 and 2008 which uses ASCII files with additional special formatting information.  It was useful because it allowed cross-platform compatibility (a “common denominator”) for virtually all Microsoft and other word processors (even Macs).  Almost every PC word processor can still write, read and save documents in some version of RTF. The document extension is “.rtf” and it enables exchange between, say, MS Word and Corel Word Perfect programs.

RICKROLLING:  Tricking someone into clicking a link under the impression that it will lead to something interesting, but instead serenades the viewer with Rick Astley’s “Never Gonna Give You Up”.  There have been a number of successors to this “bait-and-switch” scenario, the more popular ones being “Trololo” and the wheelchair cliff scene from “Mac and Me”.

RING:  The “security” rings in the Windows O/S (between 3 & 0) which control the degree of privileges granted to specific software (which may include malware) run on the system.  See, SECURITY for more.

RINGTONE:  Also, sometimes, Mastertone, Realtone.  An audio file in MP3, AAC, WMA or other sound format which creates a sound when there is an incoming call, usually on a cell phone.  While the market ramped up to almost $650 million by the mid-2000s, it has fallen to only about $165 million in 2012 and is steadily declining, due to more texting and less use of phone calls and it’s being less of a novelty these days.

“RIP”:  Verb. Usually a colloquial term used with respect to CDs and DVDs, meaning to copy data onto the CD/DVD media using drive made for that purpose.   The noun “rip” actually refers to the copied content, in its destination format (which may be different from the source format).  For how to do this, click HERE.

RIP:  Routing Information Protocol.  A now obsolete networking routing protocol established in the late 1980s but still used on some older home and small office routers.  It is used to share information between devices on small networks that use multiple routers, sending a request on Port 520 to which the other routers respond with a complete route table.  Unfortunately, RIPv1 has been used to launch DDoS attacks on some hosts and can be a security risk.

RIR:   Regional Internet Registry.  A not-for-profit organization that oversees the IP address space (IPv4 and IPv6) across the five separate geographic regions across the globe (ARIN, RIPE, APNIC, LACNIC and AfrNIC) which, together, are known as the NRO (“Number Resource Organization”).  See ARIN, which is the RIR for the United States.  The RIRs were established in the 1990s by the ISPs in response to the rapid growth of the Internet, and tasked with the establishment of consensus and consistent global policies for address space allocations and assignments, among other things.

RISC:  Stands for Reduced Instruction Set Computer.  This is a type of computer architecture (system design) that reduces chip complexity by using simpler instructions to perform complex instructions that were previously performed by CISC (Complex Instruction Set Computer, what else?) computers.  This is done because the microcode layer and associated overhead is eliminated.  It is used often in cell phone processors.  See also ARM and SoC.

RISER BOARD/CARD:  Generically, a printed circuit board that rises perpendicular to the main or mother board on a computer, such as a modem, sound or video card.  See Main Board for more.  Originally, however, riser boards were a type of board specifically used with the older LPX type motherboards for the purpose of adding additional expansion cards to the computer’s architecture.  The subsequent ATX motherboards eliminated riser boards, as the expansion cards could then be connected directly to the computer’s main board without a riser board.

RJ:  Stands for Registered Jack, those modular plastic connectors at the end of RJ 11telephone (RJ 11) and Ethernet (RJ 45) cables.  Although technically those are known as plugs (left in the photo), the receptacles (right) are the jacks (see punch down blocks for more about this).  Interestingly, although the RJ 11 is the de facto industry standard for wired telephone handsets, the handset jack itself is not an RJ at all since it was never intended to connect directly to the service line, and is actually a “4P4C [4 pin 4 connector]” connector. RJ 11 is for a single line, RJ 14 for two lines and RJ 25 for three lines.  RJ 21 is the standard for a modular connector using 50 conductors (called an Amphenol connector, named after its primary manufacturer) for 25 line (or less) 1A2 key telephone systems (the ones with the flashing light buRJ21 connector horizontalttons quite common in offices at one time).  [Photo at right]  Some older pre-USB computer printers use a shorter 36 pin version known as a Centronics connector.  See also punch down block.


RMU:  Rack Mount Unit, or 1.75 inches of a rack mount.  See also M6 holes and “U”.

Lawrence G. Roberts old photoROBERTS, LAWRENCE G.:  One of the “Fathers of the Internet”, employed by J.C. R. Licklider at DARPA in the 1960s to move the Internet from concept to reality.  He worked with researchers Leonard Kleinrock and Paul Baran in the U.S. and Donald W. Davies in Britain to develop “packet switching” to solve bandwidth constraints by packaging transmissions into small packets and shooting them over the same wires. Then, in order to develop a network protocol that would impose order on the packet switching chaos, he relied on Vinton G. Serf and Robert E. Kahn, who, while at DARPA, created TCP/IP, the same technology still used every day today.  The hardware end was designed by Bolt, Beranek & Newman (”BBN”) which built the very first network switches.  The test hardware was sent to Kleinrock at UCLA and Douglas C. Englebart (designer of the first mouse) at the Stanford Research Institute in 1969,  BBN got the first East Coast “Node” in 1970.  In 1971, BBN took the Net a step further when Ray Tomlinson wrote what was the first e-mail program.  After that, scientists and others inundated the Net and it was off and running for everyone.  Roberts left DARPA in 1973 to start Telnet Communications Corp, (originally a BBN subsidiary, now part of Sprint Corp.) which was the first commercial packet-switched network; then, in 1999, he started Caspian Networks, Inc. to develop switches for multimedia traffic for streaming video and audio. 

ROBOCOPY:  Microsoft says this stands for “Robust File Copy.”  This is a feature in Windows 7 which allows a user to move a cloned document folder (including sub folders) across the network.

ROBOT:  “Bot” for short.  Generally, any browser program which follows hypertext links and accesses web pages, but is not directly under human control.  Example: Spiders, the “harvesting” programs which extract e-mail addresses and other data from web pages and various intelligent web searching programs.

ROBOTS.TXT:  A text file stored in the top level directory  (“TLD”) of a web site to deny access by robots to certain pages or sub-directories of the site.  Only those robots which comply with the Robots Exclusion Standard will be read and obey the commands in this file.


ROBOTICS:  The science of machines performing human tasks, particularly structured ones.  Robots have taken over not only manufacturing, but also wall street trading, military drones, warehouses and many other tasks that could be easily automated.  This has become possible in part because of the increased power of computing.  On the plus side, the cheap cost of robotics may make it possible to take American jobs back from foreign labor.

ROBUST:  A term applied to both computer software operating systems and programs that means it performs well under both ordinary as well as unanticipated conditions. A “robust” application can operate for prolonged periods of time without crashing and, if it does, will not affect other programs.

Rocket MailROCKETMAIL:  One of the original free webmail services, developed by Four11 Corporation, a major competitor to Microsoft’s Hotmail until it was later acquired by Yahoo Mail in 1997 for $92 million.

ROKU:  A set-top box allowing customers to view Internet delivered movies and TV shows instantly on their televisions.  To compete with Google, in 2016 Roku introduced five new set-top boxes loaded with features (see C-Net review HERE), and the $30 Roku Express is even cheaper than Google Chromecast (although it’s quite slow, especially with Netflix), and actually includes a remote, while higher-end Premiere and Ultra boxes sport 4K and HDR video. Of course, if you have a smart TV, you don’t need it.  See FAQ #46 for more.

RoHS COMPLIANT: Refers to the Restriction of Hazardous Substances Directive (2002/95/EC): Adopted in February 2003 by the European Union and effective on July 1, 2006, this directive restricts the use of six hazardous materials (lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls and polybrominated diphenyl ether) in the manufacture of various types of electronic and electrical equipment.  Often linked with the Waste Electrical & Electronic Equipment Directive (WEEE 2002/96/EC), which sets collection, recycling and recovery targets for electrical goods and is a part of an EC legislative initiative to solve the problem of huge amounts of toxic e-waste generated by electronic equipment.  The WEEE recycling logo is shown above.

ROI:  Return On Investment.  The monetary benefits derived from having spent money, often annualized.  There are many formulas to calculate ROI.

ROM: Read Only Memory.  See Firmware, CD.

RONDEZVOUS: See Bonjour.

ROOM 641A: A telecommunication interception facilitRoom_641A_exteriory operated by AT&T for the NSA, beginning in 2003 until it was exposed by former AT&T technician Mark Klein on the “Frontline” news TV show, resulting in a class action lawsuit against AT&T in 2006 by the Electronic Frontier Foundation (see Associations).  Room 641A was physically located at the SBC Communications building at 611 Folsom Street in San Francisco, and allegedly at many other places throughout the U.S.  Photo at right,courtesy Wikipedia.  It was alleged that the NSA engaged in a massive illegal program to wiretap and data mine the communications of millions of Americans.  See also, Carnivore, Echelon, PROMIS, PRISM, LAWS.

ROOM M-42: The hidden room in NY Grand Central Station’s sub basement, not shown on any plans, which hid the computer used during WWII to control troop movement via train and which Hitler attempted to destroy with spies who were left on Long Island by submarine.  For more, see Who Invented the First Computer in this site.

ROOT (DIRECTORY):  In a hierarchal computer file system, the first or topmost directory, the directory that includes all of the other lower sub-directories.  In Windows computers it’s usually the “C:\” directory.  It’s like the “root” of a tree, the starting point from which all branches originate. Subdirectories below the root directory are child directories, and any directory above any other directory is a parent directory.

ROOT (VERB):  Rooting” is the process of allowing users of smart phones, tablets and other devices running the Android operating system to attain privileged control (known as “root access”).  Rooting, which is like administrator access in other operating systems, is often used to allow users to override the limitations of the installed operating system so that the device can be used for certain applications or features not available off-the-shelf (e.g. USB tethering).  It’s not the same thing as jailbreaking, which is purposely evading prohibitions against changing the operating system (al la Apple).

ROOTKIT:  SEE SPYWAREA specific type of malicious software that is used by hackers to remotely access infected computers for nefarious purposes.  They aren’t usually discovered by ordinary anti-virus software because they reside in the “rootdrive of the computer, hidden from the levels of files which ordinary contain viruses. Because of this, they can disable anti-virus programs.


ROUTINE:  Also, sometimes, a procedure, function or subroutine.  A section of a software program that performs a particular task.  Programs are usually comprised of modules, each of which can contain one or more routines.

RPC:  Remote Procedure Call.  This service is a part of the Windows operating system that allows Windows’ underlying processes to communicate with one another and across the network with each other.  NEVER disable this service.

RPG:  Role Playing Game.  A game where the player plays the role of someone in a story, sometimes in the character of an avatar. Also, MMORPG, which stands for massively multi-player online role-playing game.

RSA:  A type of encryption algorithm named after its authors/inventors - Ron Rivest, Adi Shamir and Leonard Adleman (“A Method for Obtaining Digital Signatures and Public-key Cryptosystems”. CACM 21,2; 1978).  It is one of the most commonly used encryption and authentication algorithms by web browsers.  Essentially, the algorithm involves multiplying two large prime numbers which are then mathematically processed to derive a set of two other numbers that constitute a public and a private key.  Both keys are required for encryption and decryption, but only the owner of the private key needs to know the private key, which is never sent across the Internet.  In addition to encrypting messages you can authenticate yourself with a digital certificate so that the recipient knows that it is the correct sender who sent the message.  Also a computer security conference held each year (see Associations).

RSS:  Short for “Rich Site Summary”  [more recently renamed Really Simple Syndication] this term refers to a technology that allows web users to receive ongoing, constantly updated information from multiple selected sources through one RSS “Feed” that the user subscribes to which selects various sources to be accumulated (or, as they say, “aggregated”).  They include sources like podcasts (the platform from which RSS was derived, using push technology). Analogous to news syndication, which allows the sharing of news collected from various sources into a single feed (think “UPI” & “API”).  Basically, an RSS feed allows users to keep up with all their favorite web sites, news feeds, podcasts, blogs and any other type of constantly updated web presence in an automated manner rather than manually checking each one separately, all on the same page.  Every RSS is a feed, but there are other types of feeds besides RSS (e.g. HTML feeds).  You read the RSS feeds with a RSS reader.  There are several popular readers:  Google Reader (discontinued July 1, 2013; Pulse; Feedly; Newsblur; IFTTT; and, of course, Internet Explorer’s built in RSS function (since Iex7).  See also feed, Aaron Swartz.

RTP: Real Time Protocol; also Secure RTP (“SRTP”)  See SIP.

RUBY: Originated and developed in Japan by Yukihiro “Matz” Matsumoto, this is a general purpose object-oriented programming language that combines Perl syntax with Smalltalk-like features.

RUBY ON RAILS:  This is an open source framework for web development using Ruby; it’s principal advantage is speed and ease of use as opposed to Java-based frameworks.  Twitter, Shopify and GitHub were all originally developed using Ruby on Rails.

RUGGEDIZED:  Refers to equipment, most often laptops, that have been built to withstand shock resistance, temperature extremes, drops, vibration, dust, moisture, etc. in field or outdoor use.  High end laptops should comply with specifications such as MIL-STD-810F, ASTM D 4169 and IEC 60529.  Toshiba, Panasonic and Fujitsu all make a ruggedized line of laptops.

RULES OF THE INTERNET:  A series of rules, observations or conventions  pertaining to the Internet that have accumulated through general usage.  [Kind of like Gibbs’ Rules in the NCIS TV show.]  Things like “Anything you post will eventually go public, can and will be used against you, and will go viral if it’s epically stupid,” “There are facts on the Internet if you know where to look,” “Anything can be made better by adding cats,” and “Nothing is Sacred”.   A tongue-in-cheek compilation of some thousand of these rules can be found HERE.  Click HERE for my own ten commandments about the Internet.  Additional rules were also developed by the hacker group Anonymous. The most famous ones are discussed below:

RULE 30 (Of the Internet):  If there are no pics of it, then it didn’t happen.

RULE 34 (Of the Internet):  An observationRule 34al “rule” developed in 2005 by a 16 year old Englishman named Peter Morley-Souter that “If it exists, or can be imagined, there is Internet porn of it”.  [There is, for example, alien goat sex, potato porn, Clippy sex, etc.] He derived the law when he came upon a Calvin & Hobbes cartoon (at right, redacted and published by The Washington Post with permission from Peter Morley-Souter) and turned it into a widely circulated web comic.  It also has a corollary, “If no porn is found at the moment, it will be made”.

RULE 63 (Of the Internet):  For every female character, there is a male version of that character and vice versa.

RUN (CABLE):  See Drop.

RUN DLL32:  Run Dll32.exe is a Windows system component that can run dynamic link libraries (“dll’s” which were created when installing programs) and similar software as if they were standalone applications.  Loosely speaking, it’s a utility used as a general tool to launch collections (“libraries”) of task-specific tools. When this file becomes corrupt, it severely damages the Windows operating system and it must be repaired or even reinstalled.

RUN LINE:  The selection on the Windows Start Bar that allows a computer user to run a Windows program or utility.  To be distinguished from a command line, which runs a DOS program from outside the Windows operating system.

RUNTIME:  Refers to when a program or app is “running”. 

RUNTIME ERROR:  A software or hardware problem that prevents a program from working correctly.  It can occur, for example, if you are running two software programs that are incompatible, if the computer has memory problems, or perhaps has been infected by malicious software.

RUST:  A programming language similar to C or C+, intended for writing low-level, permanent code that is safe by default.





























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