A screenplay is a script for a film or television show. It includes dialogue as well as stage direction and character actions and movement.
Screenplays have a specific format, although there can be slight variations based on factors:
1. Type (i.e. film, multicam TV, singlecam TV, etc.)
2. Destination (studios and networks often have specific idiosyncrasies)
3. Origin (different countries use different standard paper size, for instance)
4. House style, specific to a certain TV show, for example.
Final Draft, Celtx, and Movie Magic are examples of word processors designed specifically to help writers format screenplays properly.