Juxtaposition involves placing two contrasting objects or elements side by side to allow the viewer to interpret their relationship. It can involve contradicting objects, colors, ages, genders, or other aspects within a single frame. Effective juxtaposition uses starkly different elements like Big Ben next to a modern skyscraper, mixing dark and light skies, or pairing an elderly person with a young child to thoughtfully contrast and compare. The document provides examples of juxtaposition in photography and analyzes several of the author's own pictures that employ color, environmental, and gender contrasts.