post-production - Major post-production companies include, Reference

The completion stages of a film after shooting up to the first public showing. The picture is finally edited to the director's satisfaction, and the original negative cut to conform; music and sound effects are recorded and mixed with the actors' dialogue in dubbing the final track. This magnetic record is transferred to a photographic sound negative for printing along with the cut picture negative to produce the answer print. After the director's approval, a show print is made for the premiere presentation. Corresponding stages are followed for a video production: the editing and sound track preparation results in the ‘on-line’ transfer of the original videotape to produce the final master for transmission or duplication.

It is the general term for all stages of production occurring after the actual recording and ending with the completed record, film or video. Adding audio sound effects - like ADR, Foley, sound design and sound designers' actions. Color grading, and neg cutting the final master copy from which release prints will be made (although this may be made obsolete soon by digital cinema technologies).

Typically, the post-production phase of creating a film takes longer than the actual shooting of the film, and can take several months to complete.

Other film production stages include (very broadly) - financing, pre-production, writing the screenplay, rewriting the screenplay (repeat), and the actual shooting.

Major post-production companies include

Ascent Media Digital Domain EFilm Framestore CFC Industrial Light and Magic and Skywalker Sound The Mill Weta Digital

Reference

Paul Read. A Short History of Cinema Film Post-Production (1896 - 2006).