For me montage is a filmmaking technique that uses a series of short images, collected together to tell a story or part of a story. This is usually used to advance the plotin some way without showing all the detail of what’s going on – for example, you might show a series of quick shots in which an inventor is scribbling at his desk, then poring over a book on the train, then staring intently at a computer screen. Without using any words, the filmmaker shows us that this inventor is working intensely on his latest project.
Sometimes, people use the word “montage” more loosely to mean any collection of small, discrete elements in a story or poem. We can call this “literary montage.” However, the term usually refers to film rather than literature.