CableCARD: A smartcard with an embedded chip that descrambles premium channels. You rent a CableCARD — which plugs in to a slot on your HDTV — from your cable service provider.

CAT-5e: A long-run Ethernet cabling system most commonly used in homes to carry audio and video signals for computer networks and a whole-home theater network.

CAT-6: A long-run Ethernet cabling system used to carry audio and video signals for computer networks and a whole-home theater network; suitable for very fast computer networks.

central wiring panel: A place in your home where you locate the infrastructure devices that enable you to connect your home theater to other parts of the house in a whole-home theater system.

chrominance: The color portion of the two-component video signal that runs through a video cable (the other component is luminance).

coaxial: 1. (noun) A digital audio interconnect cable with RCA jacks on each end, used to connect home theater components to the A/V receiver. 2. (noun) A cable (also called coax) with an F connector, used to connect a cable TV feed, antenna, or satellite dish to a home theater.

codecs: Programs that can compress (for efficient storage and distribution) and decompress (for playback) music and other file types into either lossless or lossy digital files.

color depth: A measure of the number of digital bits used to store the color information for a high-definition TV source.

comb filter: Separates the color and brightness parts of a video signal into their component parts and sends them to the appropriate internal circuitry. Comb filters are more effective than notch filters, and include these types: 2-D, 3-D, and digital.

component video: A type of short-run analog video connection that provides one path for brightness information and two separate paths for color information. These cables typically have red, green, and blue connectors; a better alternative to composite video or S-video.

composite video: A type of short-run analog video connection in which both color and brightness (the two components to a video signal) are combined into a single signal. The comb filter inside a display then separates these signals. These cables are usually color-coded yellow.

contrast: The level of white that you see on a video display. The contrast control on a display enables you to adjust this setting.

contrast ratio: A numeric ratio (such as 800:1) that measures how well a display can show bright brights compared to nuanced darks. A higher ratio is better, but this measurement isn't standardized so you can't easily compare numbers between manufacturers.

controller: Short for A/V controller. A device that performs switching (between audio and video sources) and preamplification tasks in a home theater. One of three separate components (along with a power amplifier and radio tuner) that can be used in place of an all-in-one A/V receiver.