HDMI stands for High Definition Multimedia Interface. This is a new interface standard that is employed for use with audiovisual equipment. It is usually seen in high definition television sets and also home theater systems. HDMI comprises of 19 wires that are wrapped into one cable that looks much like a USB wire. With the wire configuration it is possible to carry a signal with a bandwidth of 5 Gbps or gigabits per second. This amount is more than two times the bandwidth that is transmitted through multichannel audio and video. This means that HDMI is a future proof technology. This alone makes HDMI a far more superior choice compared to the other technologies like component video, S Video and composite video.
HDMI is an all digital signal that is transmitted without any compression. Compare it with its predecessors, which are all analog interfaces. Because of its digital “roots” HDMI can preserve the source signal and practically remove any kind of analog conversion in order to transmit the best possible picture.
The previous A/V interfaces (component, composite, and S video) would require audio cables that are separate from the video cables. With HDMI, the capacity for a lot of bandwidth and the speed at which it is transmitted is so great that audio signals can also be transmitted at the same time as the video signal immediately. In fact, even high quality surround sound with up to eight digital audio channels.
But this early, development for a new HDMI standard is already underway, whereas the HDMI Type A will be comprised of 19 wires, the upcoming HDMI Type B will have 29 wires.