What is HDMI?
HDMI is a high speed digital interface for the transmission of high quality digital audio and digital video. So if you plug your DVD player, your PlayStation 3, your satellite or cable TV box, or even your computer up to a modern HDTV with a single HDMI cable, then the sound and picture will all work. The HDMI plug only has a single small connector so it's nice and simple. Before HDMI, you had to hook up three separate connectors for just the video and two additional RCA plugs for stereo sound. Instead of the two RCA plugs, you could also use an S/PDIF optical cable for the sound but it still adds a lot of cable complexity and clutter compared to a single HDMI cable.