The term montage is used in three different ways. A photomontage is a composite image produced by blending multiple images to create a fully realized whole. A film or television montage involves a sequence of shots which have been edited to follow each other in rapid succession. A radio montage is similar to the film type, except that it uses sounds rather than images.
The art of making a photomontage is almost as old as the medium itself. Early photographers combined multiple images to achieve desired artistic effects or looks, and artists picked up the idea, creating a variety of scenes. One advantage of photomontage is that it can be used to juxtapose or overlay images which could not be seen together in real life, adding a note of surreality to the finished image. For example, a simple photomontage might be made by placing an image of Isaac Newton inside the International Space Station, making a commentary on advances in the sciences.
The advertising industry relies heavily on this art to produce images for campaigns. Editing together multiple images, an advertiser can evoke a specific mood or feel with an advertisement which might not be possible with a single straight image.
Film montage appears to have emerged in the work of Sergei Eisenstein, a talented Russian filmmaker. He often used this technique to create a symbolic effect which was meant to trigger a specific response in the user, while Hollywood picked up the concept and used it to illustrate the passage of time. For example, a filmmaker might film the pages of a calendar next to a window flipping over in quick succession, with the scene outside the window changing to reflect the change of the seasons. Film montage might also be used to express a sense of movement and travel, as in the case of many noir films featuring train montages.
Radio montage is used for much the same reason that the technique is utilized in film: to move the story along, suggest the passage of time, and possibly to evoke specific emotions in the user. Creating montages for radio can be tricky, as the editor needs to find evocative sounds which will be interpreted by listeners without any visual cues. An adaptation of a train sequence for radio, for example, might intercut sounds of wheels clacking on rails, a train whistle, release of steam, and train bells.