codec;

Codec is a technical name for 'compression/decompression'. It can also stand for 'compressor/decompressor' and 'code/decode'. Essentially, a codec is a computer program that both shrinks large movie files and makes them playable on your computer. Codec programs are required for your media player so that they are playable on your computer. This is useful since large video and music files are difficult to transfer across the Internet quickly. These mathematical codecs were built to encode (shrink) a signal for transmission then decode it for viewing or editing.

They are used in: videoconferencing, streaming media and video editing applications.