Screenwriters create! They write and develop worlds for themselves and the reader to enjoy. A screenwriter lays the foundation for all of the films and television shows we watch by writing the scripts the actors work from.
There are two types of scripts: Original and Specs. A spec script is written for a show already airing. It's the screenwriter's way of creating the episode they want to see. It also shows the writer's ability to match their voice with other writers. An original script is well an original work created for film (short/feature), television (pilot / made for TV), or online (YouTube / Short Platforms). These aren't the only areas that use scripts, commercials, podcasts, and video games all use scripts.
