Montage is from the French for ‘putting together’ and in film they are generally used to suggest a longish passage of time in a short period. This is done through a series of short shots edited together, normally without dialogue and often with some song playing over the top. Basically to move the story forward as quickly as possible.
There is also a Soviet montage theory, which works on the idea that in a montage the images are shown one after the other, but that they are interpreted as a whole, or being on top of each other. In this way, symbolic meaning is formed.
The training (or sports) montage, that Phauna was aluding to, is a common element in action films; and whenever I think of montage, I think of Team America.
So what are the best film montages of all time, in your opinion? Top Gun? Ghostbusters? Groundhog Day?