HD Radio: A digital radio broadcast that can be incorporated into a home theater without paying a monthly fee. Not all receivers are capable of receiving HD Radio.

HDCP: An acronym for High-bandwidth Digital Content Protection. HDCP is a strong copy protection system used with DVI. It can limit your ability to make a digital copy of what you're watching.

HDMI: An acronym for High-Definition Multimedia Interface. HDMI is a short-run analog video interconnect that is used to connect home theater components to high-definition TVs. The HDMI interface carries both audio and video signals over the same cable, and is quickly becoming the connection of choice for high-definition systems.

HDTV: High-definition TV. A subset of ATSC technology. The HDTV offers spectacular high-definition picture quality in a widescreen format and is now considered a must for home theater systems. HDTV content is available in the form of broadcast programming and Blu-ray discs.

Home Theater PC; HTPC: A personal computer (that can be considered a high-quality source device) that you attach to the A/V system of your home theater. An HTPC can feed audio and video content into (and receive content from) your home theater system. You can create a home theater PC out of an existing PC, purchase a new home theater PC, or even build your own.

home-theater-in-a-box; HTIB: An integrated home theater system that bundles together a receiver, DVD (or Blu-ray) player, surround-sound speakers, and cables. Other configurations are also available.

hotspotting: A characteristic of the screen in a front-projection system in which one part of the screen is brighter than the other parts. Choose a low-gain (less-reflective) screen to avoid this problem.

hub: The centralized connection point for the audio and video equipment in a home theater, which is typically the A/V receiver.