The “sizzle” of the Web is multimedia – the use of sound, images, graphics and video to make Web pages “come alive”.

Audio and video can be used in Web pages in a variety of ways. Audio and video files can be embedded in a Web page or placed on a Web server so that they can be downloaded on-demand.

Common video file formats include MPEG (Moving Pictures Experts Group), QuickTime, RealOne Player, AVI (Audio Video Interleave), and MJPEG (Motion JPEG).

Audio formats include MP3 (MPEG Layer 3), MIDI (Musical Instruments Digital Interface), WAV (Windows Waveform), and AIFF (Audio Interchange File Format).

Encoding and compression determines a file’s format. An encoding algorithm or codec (compressor/decompressor) transforms raw audio or video into a format that Web browsers (or programs accompanying a Web browser) can interpret and display. Different encoding levels and formats produce file sizes and quality that are ideal for different applications.

Some codecs are available to the public in the form of encoding applications. Most encoding applications compress audio and video files. Some serve as format converters, converting one file format into another.