Media Composer is a non-linear editing (NLE) software application developed by Avid Technology. First introduced in the late 1980s and widely adopted in the 1990s, it has become a prominent tool in the professional editing landscape, particularly in the film, television, and broadcast industries. Media Composer is used in a variety of production environments, including feature films, television shows, documentaries, and streaming service content.

Its interface, functionality, and workflow are designed to accommodate the complex requirements of professional editing, offering advanced tools for managing large volumes of footage and collaborative post-production work. Due to its widespread use in professional environments, it is often regarded as one of the industry standards for non-linear editing, particularly in Hollywood film production and broadcast television. The software's features and workflow are closely aligned with the needs of high-end post-production, and it continues to be a favored tool among professional editors.

Media Composer was first released in 1989 as Avid/1, an offline editing system designed for the Macintosh II. According to Eric Peters, one of the founders of Avid, most prototypes of 'The Avid' were originally built on Apollo workstations. At some point, Avid demonstrated one of their products at SIGGRAPH, a prominent conference on computer graphics and interactive techniques.

Says Peters, "Some Apple people saw that demo at the show and said, 'Nice demo. Wrong platform!' It turned out they were evangelists for the then new Macintosh II (with six slots). When we got back to our office (actually a converted machine shop) after the show, there was a pile of FedEx packages on our doorstep. They were from Apple, and they contained two of their prototype Macintosh II machines (so early they didn't even have cases, just open chassis). Also there were four large multisync monitors. Each computer was loaded with full memory (probably 4 megs at the time), and a full complement of Apple software (pre-Claris). That afternoon, a consultant knocked on our door saying, 'Hi. I'm being paid by Apple to come here and port your applications from Apollo to Macintosh.' He worked for us for several weeks, and actually taught us how to program the Macs."

At the time, Macs were not considered powerful enough for video editing. However, the Avid engineering team managed to achieve a data rate of 1,200 kilobytes per second, which enabled offline video editing on the Macintosh platform.

Avid Symphony has a strong history with broadcast users because much of its design and implementation came from the scopes, monitoring, and terminology that was familiar to the television industry's online mastering process. It has since grown to include Advanced/Secondary/Relational Color Correction and Universal HD Mastering.

Avid Symphony used to be a separate product from Media Composer, purchased as a standalone system for mastering. Beginning with Media Composer 7, Symphony became integrated within Media Composer as a paid option. In 2014 when Media Composer 8 was launched along with Avid's subscription licensing, the paid option included monthly and annual subscription licenses.

The software used to be protected by means of "blesser" floppy, tied to the Nubus's TrueVista board (meaning that if the board is replaced, a new "blesser" floppy comes with the board), and later with USB dongles. As of version 3.5 the dongle is optional, and existing users may choose to use software activation or keep using their dongles, while new licenses are sold exclusively with software activation. The software ships with installers for both Mac and Windows and can physically be installed on several computers, allowing the user to move the software license between systems or platforms depending on the licensing method.