Transitions

Transitions are techniques that are used when scenes or shots are combined together. They are often used in films to convey a mood or tone to the audience. Transitions usually imply the passage of time however they can sometimes imply something else.

A fade occurs when the image on the screen gradually turns into a single colour, the colour is usually black. Typically a fade in occur at the start of a film while a fade out will occur at the end of a film.

Dissolve is a transition that is similar to fade however rather than changing the shot to a colour, the dissolve changes one shot into another shot gradually. This is usually used to create a link between two objects for example if a man was day dreaming, it would start with the a shot of the man day dreaming, followed by a dissolve which is followed by the visuals of the subject the man is day dreaming about.

The video above is a short clip from the film Psycho (1960). The film makers implemented a cross dissolve for the ending of the film and rather than fade to black, they chose to cross dissolve from one shot into another. This is purely for the ending of the movie as the first shot is Norman Bates (the main character) staring at the camera smiling as if he assumes he has gotten away with murder, the shot then dissolves into a car being lifted out of a swamp. 

A wipe is a transition that involves one shot replacing another, travelling from one side of the frame to the other. These aren't very common in films as they seem unprofessional and there are better options out there. Usually the wipe will imply the passage of time or is used when the next shot is in a different location. George Lucas is known for using wipes in his Star Wars films.

The video above gives plenty of examples of various wipes used by George Lucas. Many of them imply the passage of time or allow the image to smoothly transition into another image from another location. However they don't look professional which is why many film makers tend not to use wipes in their films.