Back in the 1980s, to connect a computer to a monitor (“screen”), you simply placed the blue VGA connector into the back of the computer and you had video. It may have started with RGB or RGBY video or the later versions of VGA, but it was pretty standard and useful for most purposes at that time. However, as more people used the internet for movies, YouTube and gaming, faster video processing and more colors became desirable. Due to this, the move from analog to digital video became inevitable. [This progression is much like the connector progression from DIN to PS2 to USB keyboard and mouse connectors over the same period.]
By the 2000s, most computers had DVI connectors (“digital video”) and used adaptors to connect the VGA monitors to the video port of the computer. By the mid-2000s, DisplayPort and HDMI connectors also became standard ports on most video cards. At the same time, the amount of video RAM on the card itself, went from 512Kb to over 4Gb because it was not only faster, but didn’t detract from the available motherboard RAM.
But this discussion is only about video connections.
Once gain, what type of video port you decide to purchase (if there’s any choice) depends on what you want to do with your computer. Essentially, the “quality” of the picture will be the same in terms of resolution regardless of which type of connector and cable you use. For example, 1,920x1,080/60 will look the same on your monitor or TV regardless of whether it is received over DisplayPort or HDMI. If it works, it works. And most TVs dumb down a higher resolution signal if it can’t process it, so you’ll always get a picture but possibly not at as high a resolution as your card may transmit. There may also possibly be some cable distance issues where it won’t work with your setup, but then it just won’t work! But when you get there, all things being equal, the picture “quality” will look exactly the same no matter what type of port you select.
Here are your current choices:
VGA: Old analog technology. Avoid it, if possible. Why? Because it’s analog, you’re not likely to see a pixel-perfect image on an LCD monitor, even with a VGA adaptor. Many businesses still use these legacy monitors because they believe that they’re only viewing text and, for the inexpensive cost, it’ll be sufficient. But there is a very real difference, even for text.
HDMI: Because this type of cable is relatively inexpensive, carries both audio and video and can run to a reasonable length, these are best for viewing on a TV screen. And these days, most newer computer monitor have HDMI ports as well. But there are limitations that make it less useful for extremely high resolutions and frame rates (which won’t affect any but the most devoted gamers). Most TVs these days have HDMI 1.4 connections with a maximum 3,820x2,160 resolution at 30 frames per second. When HDMI 2.0 come out with newer TVs, you will be able to do your 4K TV at 60fps, but right now, you’re limited to 30fps.
DISPLAY PORT: This computer connection is about the same speed and the cables are about the same expense as HDMI (above), the are for computer monitor connections, not connections to TVs. The cables, which also carry audio, run at 3,840x2,160-pixel resolution at 60fps, if you have at least DisplayPort 1.2 and the Multi-Stream Transport feature, so it’s got a faster FPS than HDMI.
DVI: Depending on your equipment, the signal strength is about the same as HDMI, although it depends on whether your cables and hardware are “single-link” or “dual-link”. But DVI doesn’t usually carry audio, so you’ll need separate cables and either built-in audio or an add-on card for that.
THUNDERBOLT: The Intel/Apple is technically only available on Apple’s Thunderbolt Display monitor, although more compatibility is promised. The connection is compatible with Mini DisplayPort.
S-VIDEO: Simply for the purpose of definitions, let’s rule out cables like S-Video. S-Video (a/k/a Super-Video and Y/C) is a signal standard for only standard definition video (e.g. 480i/576i), and it requires separate audio cables. Same for the other types of legacy cables, Composite Video and Component Video. All relate mostly to televisions and all are obsolete.
ADAPTERS: If you still have legacy monitors, there are adapters for video cards with these current connections. Unlike most adapters, they appear to work well. So you probably can connect your old 17in VGA monitor to a DVI or Display Port connection on the back of your new computer, although it won’t provide the high definition video that your computer is capable of producing.
For photos of the various connectors and cables discussed above, see the links.