As an A/V connection standard, HDMI has its downsides: limited cable length, glitches, slow switching, and version upgrades that make new gear incompatible with old stuff — the list goes on. But a major upside is that one interconnect can handle the jobs previously carried out by a thick wad of cables. In its most current version, HDMI 1.4, a single link will convey high-def video/multichannel audio, link devices to a local network (HDMI Ethernet Channel), and route audio signals from a TV back out to an A/V receiver (Audio Return Channel). Sweet!
But any TV making the hook-up also needs to be plugged into a power socket. That means an additional wire, plus the logistical problem of locating a TV near an AC outlet — or, for a wall-mounted installation, of embedding one within the wall (a task that generally requires the services of an electrician). Wouldn’t it be great if HDMI also carried power?
HDMI can’t. But HDBaseT can.