A Scene heading, also known as a Slugline, tells the reader where a scene takes place. Examples:
EXT. NEW YORK STREET - AFTERNOON EXT. VILLAGE SQUARE (ROME) - NIGHT INT. GRIFFIN INC. - CONFERENCE ROOM - CONTINUOUS
-Format: Scene headings are in all caps and left aligned. They are placed at the beginning of each new scene.
-The first part of a scene heading indicates whether the scene is interior (INT.) or exterior (EXT.)
-The second part specifies the location.In the first example, the location is a street in New York. Sometimes, the location needs to be more specific. In the second example, the location is a village square in Rome. Rome is put in parenthesis because it establishes the larger setting encompassing the entire story. Once it is established the story takes place in Rome, the information inside the parenthesis can be dropped. In the third example, the more general location is followed by a hyphen then the more specific location.* This is common, but not always necessary.
-The third part specifies the time of day. Usually the time is general, such as MORNING, DAY, NIGHT, AFTERNOON, etc. It can also be more specific (if necessary) such as MIDNIGHT, 1:30PM, DUSK, etc. CONTINUOUS shows that the scene takes place immediately following the previous scene and no time has passed. MOMENTS LATER is also used to show a small jump in time.
*I would like to note there are other ways of specifying location that are acceptable in the industry. This just happens to be the way I prefer.