High-Definition Multimedia Interface. An HDMI cable has 19 wires wrapped in that single high-bandwidth cable.
It sends an uncompressed, all digital signal, and can carry not just uncompressed digital video, but up to 8 digital audio channels as well.
So that single cable can take clear, uncompressed digital video and output it on your monitor exactly as it's sent, without compression, conversion to analog etc. And it will play your sound too.
The generally available so far is Type A, current standard, with 19 wires. Type B will have 29, yes TWENTY-NINE cables, but applications will be professional, like movie studios etc.
But for now, HDMI is the top tier of quality audio and video input and output.