The word “beat” has a few different specific uses in screenwriting. But in general, all forms are a type of single, small unit.
In screenplays, a “beat” is the smallest unit of measurement. If a character sits down at a desk and picks up a pencil, that is two beats.
A “beat sheet” is a type of outline where each “beat” is an individual unit of plot. So a beat sheet is an outline made with the specific purpose of breaking plot points down into their simplest forms.
The word or parenthetical “beat” is often used in screenwriting to signal a brief pause in a character’s speech or action. While this is acceptable, many screenwriters believe it is best used sparingly. Often, pauses can instead be expressed through action. For example, a character can wipe his brow in the middle of a line instead of “taking a beat.”
* [WTF is a beat sheet?](http://johnaugust.com/2010/wtf-is-a-beat-sheet “WTF is a beat sheet?”)
* [Pause vs. beat](http://johnaugust.com/2007/pause-or-beat “Pause vs. beat”)
* [Using parentheticals](http://johnaugust.com/2003/using-parentheticals “Using parentheticals”)
* [Are parentheticals overused, cont’d](http://johnaugust.com/2010/parentheticals-contd “Are parentheticals overused, cont’d”)