180 Degree rule

For the 180 Degree rule an imaginary line is created which is perpendicular to the cameras view point and called the axis. The axis connects two characters and the camera always stays on one side of it for each shot in the scene. The camera can only move 180 degrees along the axis. Breaking this rule is referred to as 'crossing the line'. Crossing the line can cause confusion for the audience due to the image being flipped meaning that if two characters are shown from the front and the rule is then broken, the character who was originally on the right would now be on the left. This could also mean that the characters eye lines would not match in both shots. Because the rule had been broken the other character looks like they are looking in the wrong direction in which they should be looking
An example of this is: