180° Rule

The 180-degree rule is a technique used in film making and is a guideline that helps link the spatial relationship between two characters or, a character and an object within the scene. This guideline is made up of an invisible line called an axis that helps connect the characters and keep them in the right position. If you keep the camera on one side of the axis for each shot, the first character would always be frame right of the second character or object, which would then be frame left of the first character throughout the scene. If the camera then passes over the axis this would be called 'jumping the line' , which then breaks the 180-degree rule. By using the 180-degree rule it helps the audience to take in the movement happening within the scene behind the characters that otherwise wouldn't be seen.

Example-

Link:- https://www.youtube.com/watch?v=ApUk8-XNS_w