High Definition Multimedia Interface, or HDMI, is a category of cables allowing for the transfer of high definition uncompressed audio and visual content from a digital source signal to a visual display or audio output (monitor, speakers, etc.).
There have been a few different “versions” of HDMI cables, but each new version maintains the same shape and size while increasing bandwidth and functionality. As of the newest and final formally-named version (1.4), HDMI cables are no longer labeled with their version number.
There are five main designs for HDMI cable connector types depending on the intended function of the cable:
Type-A: Designed to support high definition (as well as standard definition) television, Type-A HDMI has 19 pins.
Type-B: A cable designed to handle an extremely high definition feed (featuring 29 pins); products utilizing this HDMI type are currently unavailable on the marketplace because of an undesirably low refresh rate on the monitors (though future products are expected to return to this size once the refresh rates are improved).
Type-C: A mini cable designed with the same 19-pin construction as type A; type C cords are used with portable electronics.
Type-D: A micro cable designed with 19 pins, like types A and C, but featuring a smaller connector and different pin assignments than either of those types.
Type-E: An HDMI cable designed specifically for use with automobile video systems.
Due to the generally varied functionality of each type, it is important to match the correct cable type to the product type being enjoyed. Importantly, HDMI cables are backwards compatible with DVI cables.