The raccord is the relationship between two shots. Just as in writing, there are some rules that are kept between two shots, so the viewer doesn't get disoriented by the editing. Of course, like all conventions and rules, they sometimes are broken (check Jean-Luc Godard and some other Nouvelle Vague directors).
The most common raccord rule is that the direction of movement between shots is conserved. If you show a car crossing the frame to the right, the next shot must show the car moving to the right if it had kept going in the same direction. If you show movement to the left, it implies that it is returning to its original position.
Early movie-goers weren't so tuned to cinema's language (i.e. they wouldn't understand a close-up shot), but actually we are quite used to it. A break in raccord is often perceived as something wrong in the scene.