S-Video: S-Video offers better quality than composite video does, and most video sources except standard VCRs now have S-Video outputs. Connection is made with a special cable and multipin sockets.
Component video: This high-quality option is the minimum standard for connecting high-definition cable and satellite set-top boxes, as well as progressive-scan DVD and Blu-ray Disc players. It requires three 75-ohm coaxial cables of the same type used for composite video.
VGA (Video Graphics Array): This high-quality analog RGB connection is used primarily for computer connections.
DVI (Digital Video Interface): One of the highest-quality types of inputs. This digital video connection can attach to devices with HDMI outputs (see below) by means of an adapter. It may also be used for computer connections. Requires a special cable and multipin sockets. Some displays with a DVI input may work only with computers, so watch out for that if you plan to connect an HDTV source, such as an HD digital cable box or a Blu-ray Disc or HD DVD player. Another thing you need for guaranteed HDTV compatibility is compliance with the HDCP (High-bandwidth Digital Content Protection) system.
HDMI (High-Definition Multimedia Interface): Also of the highest quality, HDMI is DVI plus a digital audio and control link. HDMI is the dominant digital connection interface for HDTVs today. The big draw here is that you get a one-wire setup that pumps HD content into your other home-theater components too. This connection is provided on almost all current HD satellite receivers, HD cable boxes, and upconverting DVD players (those that provide 720p, 1080i, or 1080p output from regular DVDs), and it is the standard video connector for Blu-ray Disc players. The exact version of the HDMI input (for example, 1.1 or 1.3) is of little consequence on TV sets currently on the market. Of more importance to HDTV shoppers is how many HDMI inputs a TV has. Aim to get an HDTV with at least three or four HDMI inputs, to accommodate the multiple devices you're bound to accumulate.