The 180° rule, a reverse angle and Match on action.

The rule states that the camera should remain the same side of an imaginary line. The line is drawn perpendicular the camera’s viewpoint in the establishing shot of the scene. The rule enforces continuity of the film.When a camera crosses the axis, ('crossing the line'), a new shot is made called the reverse angle. All coverage should generally be shot from one side or the other of this imaginary line. The audience subconsciously forms a mental map of where the actors are located in the scene from the first master shot.

An example of this is below.

Match on Action:  Match on action (or cutting on action) is an editing technique for continuity editing in which one shot cuts to another shot portraying the action of the subject in the first shot. This creates the impression of a sense of continuity