The screenplay provides a written blueprint for the entire film making process. The script development process starts either with a Screenwriter writing a 'spec' (self-financed) screenplay for sale to a production company, or with a Producer commissioning a Screenwriter to write a screenplay based on a concept, a true story, an existing screenwork (for example a cartoon or TV series), or another literary work (such as a story, novel, poem or play).

An interesting, well-written, well-structured, and properly formatted screenplay does not guarantee a good finished film, but, without one, there is almost no possibility of success, however gifted the Director, cast and crew. Experienced Screenwriters and Production companies therefore spend many years developing stories and perfecting screenplays, and many more screenplays are developed than are actually produced.

Developing a screenplay involves painstaking visualisation of every aspect of the finished film, without any certainty of the work being realised on screen. Although the Screenwriter or Screenwriters are central to the script writing process, like every other aspect of film making, development is collaborative work and typically requires the creative input of a number of other film professionals including: Script Readers, Writer's Agents, Producers, Development Executives, Script Editors, and, eventually, Directors, who are often involved in the final versions of the screenplay and shooting script. When projects are developed as part of a Screen Agency, Broadcaster, or National Lottery funded film scheme, Development Executives from these agencies and script development staff may also be involved in the process.

Occupations found in this area are detailed below: