The purpose of continuity editing is to make the audience believe they are part of the world. Continuity editing must not get in the way of the story telling. It's purpose is to get the audience to suspend their disbelief and get carried away in the story.
The 180-degree rule refers to two characters facing each other never appearing in the same half of the frame. If they do not remain in their frame the spacial continuity of the scene will will be broken and the audience made aware of the constructed nature of the text.
The match on action cut occurs when two pieces of footage of the same thing that are filmed or framed differently are edited together.
The 30-degree rule involves changing the angle of the camera to film the same thing by at least 30 degrees to prevent producing a jump cut which will disrupt the flow and narrative. Unless a jump cut is being intentionally used.The eye-line match is where footage is matched to the eye line of the character doing the looking.
Certain shot types should be used to establish the audiences spatial understanding of the scene; Establishing shot, shot/reverse shot etc.
