What is it and why is it important to research/know what it is?

Within film making this rule is the basic guideline in which connects the relationship between one persona and another or an object on screen as part of a scene. As part of the rule there is an imaginary line which is called the axis therefore connects the characters, you then have to keep the camera on the same side of the characters otherwise the audience then becomes confused with the narrative consequently giving the scene bad reviews and no audience. If an object is involved it must remain in the center whilst the camera faces it.