Three kinds of port are common on the rear edge of a current graphics card: DVI, HDMI, and DisplayPort. Some monitors still use DVI, but it's the oldest of the three standards and no longer appears on mainstream and high-end cards these days, just the occasional low-end one. Most cards have several DisplayPorts (often three) and one HDMI port. When it comes to HDMI versus DisplayPort, note some differences. First, if you plan on using a 4K display, now or in the future, your card needs to at least support HDMI 2.0a or DisplayPort 1.2/1.2a. It's fine if the GPU supports anything above those labels, like HDMI 2.0b or DisplayPort 1.4, but that's the minimum you'll want for smooth 4K playback or gaming. Recent-generation cards from all the makers will be fine on this score. HDMI 2.1 is a newer cable spec you may see mentioned, which ups the old bandwidth limits from 18Gbps (in HDMI 2.0) to 48Gbps (in HDMI 2.1). The upgrade enables eventual 8K resolution to display at a refresh rate up to 60Hz, with 4K supported up to 120Hz. It's more about future-proofing at this point, than much else, and accommodating the latest very high-end/high-refresh 4K monitors. Note: Some of the cards from Nvidia's GeForce RTX "Turing" line (the 20 Series, a few years old now) that you may still see around employ a port called VirtualLink. This port looks like (and can serve as) a USB Type-C port that also supports DisplayPort over USB-C. What the port was really designed for, though: attaching future-gen virtual-reality (VR) headsets. It never took off and has disappeared from the latest cards.