The majority of films begin as a screenplay. Every collaborative person involved must be able read and understand its intentions so they can effectively bring their individual, creative contributions to the filmmaking process. Even if you never plan to write a screenplay, you're going to need to be able to understand the standard formatting conventions to make sense of what you're reading.
Scene Headings
Sometimes referred to as Sluglines, scene headings are written in CAPS and used to orient the reader to where the proceeding scene will take place. All scene headings will start off with indicating:
Camera Location - Interior (INT) or Exterior (EXT)
Scene Location - A brief scene description to orient the reader.
Time of Day - Day or Night
Numbering
Scene headings should be numbered as this is essential for using in all three Stages of Production. The shots that are planned in pre-production and filmed during production will be label and tracked to correspond with the scene numbers in the script. When it comes time for post-production, the Assistant Editor will be responsible for making sure the media organization adheres to the previously used scene and shot numbering.
Special Headings
There are a few other alternative Special Headings to keep an eye out for that will indicate types of montage, series, flashback, or dream sequences. These tend to be highly editorial segments to anticipate in the edit.
Action Lines
Following your scene headings you'll encounter Action Lines which are visual descriptions written in the present tense that serve to indicate essential information the audience sees or hears in the film. Within action lines you will find:
Action - subject or object movement staging within the scene
Location and Character Descriptions - essential, visual information regarding the scene and/or a character's appearance
Sounds - auditory information critical to the story
Dialogue
Sandwiched between your action lines, you'll find one of the most essential narrative components, Dialogue. Dialogue segments are comprised of:
Character Name or Cue - always be written in CAPS
Actor's Direction or Parenthetical - performance suggestions that are in parentheses under the character's name to clarify intended subtext
Speech - what the actor says
Off Screen and Voice Over
Look out for parenthetical notations to the right of a character's name written as O.S. (Off Screen) or V.O. (Voice Over). This indicates dialogue or voice over from a source not visible on screen. Noting this allows you to anticipate a plan as to whether the dialogue will be recorded asynchronously on set or if it will be recorded during post production.
The Screenplay in Post-Production
Once the film is shot, the screenplay will also serve a technical purpose in post production, as it is repurposed into a useful document prepared by the Script Supervisor called the Lined Script. This document will give the post-production team insight as to how the scenes were covered on during production, as it relates to the screenplay.
Want to see a full script?
You can review the screenplay for the short film, Authentic, here.
You can also find many full-length Hollywood screenplays at The Internet Movie Script Database, here.