Repetition is the intentional reuse of visual elements across a design. This includes things like a specific color, a shape, a spacing pattern, or a type style. The goal is for the eye to recognize these elements as related each time they appear. It's the core mechanic that makes a collection of individual screens feel like one coherent system. Repetition is closely linked to unity, but it focuses specifically on the literal recurrence of visual motifs, not just the overall sense of cohesion they create.