The process in which different shots are sequenced together into a scene, and different scenes put together into acts, and these acts put together into a film, is called editing. Tim Dirk (Filmsite.Org) describes editing as:
the process (performed by a film editor) of selecting, assembling, arranging, collating, trimming, structuring, and splicing-joining together many separate camera takes (includes sound also) of exposed footage (or daily rushes) into a complete, determined sequence or order of shots (or film) - that follows the script.
Editing creates a certain tempo for a scene. When the shot lengths are short and follows each other rapidly, then the tempo is fast. Alternatively, the tempo can be slowed by having longer shots. Typically, the average shot length is around five seconds.
Apart from just putting shots in sequence, the editor can use different ways of connecting them in sequence. These “ways” are called transitions. The most common transition is to merely put two shots next to each other, so that the shot jumps from one to the other; one shot abruptly ends, and the next shot suddenly begins. This is called a cut. Another type of transition is a fade-in / fade-out. This type of transition occur when the shot fades to black (or another colour) and the next shot gradually becomes visible. An overlap or dissolve transition occurs when the next shot becomes visible while the current shot is fading away. The two shots are therefore both visible for a short time to the audience. The wipe in / wipe out transition is also sometimes used in which one shot seems to push out another shot. Usually cuts gives a faster tempo than fades and wipes.