A video codec is either a device or software that performs compression or decompression (co/dec) of digital video. Codec programs are necessary for a media player (software or device) to play music and movies.

Historically, video would be stored as analog files on magnetic tape. Now, most video is recorded and stored in digital format. The purpose of a video codec is to represent an analog data set in a digital way. Video performance is often a balance between maximizing the video quality while minimizing file size for streaming and storage.  Additional concerns are the quantity of data needed to represent the video (bit rate), encoding and decoding algorithms, ease of editing, and minimizing data loss. All of these factors contribute to the design of codecs-for encoding and decoding.

The most common digital video codecs utilized today for broadband video playback on the various Internet connected devices include MPEG-2, H.263 / Sorenson Spark, MPEG-4 part 2, H.264 / MPEG-4 AVC, and VP6.