180° Rule

The 180° rule is a basic film editing guideline that states that two characters (or other elements) in the same scene should always have the same left/right relationship to each other.

The rule gets its name from the 180° arc that extends from a point on the other side of Beth from Arjan, to a point on the other side of Arjan from Beth, within which Beth and Arjan will always have the same left/right orientation. The 180° rule is also often called "The Line", or the "Line of Action". An imaginary line can be drawn through two characters, and the camera should stay on one side of this line. Breaking this rule is most commonly referred to as "crossing the line." It can also be referred to as "breaking the line of action", or "breaking the 180° line". In TV circles this is often referred to as "Crossing the axis" - in effect you would be able to see the camera.