Juxtaposition is when two contrasting elements are placed next to each other in a photo. Some examples of elements that can create juxtaposition include age, gender, size, materials, number, shape, color, and height. The document provides an example photo showing juxtaposition between an older building and the newer, taller, and more modern Shard building in London. It also shows three of the author's own photos intended to illustrate juxtaposition through contrasts of natural vs man-made, gender, and building size.