Rhythm
Visual tempo produced by repeating elements with controlled variation in spacing, size, or form.
In practice
Rhythm is visual tempo: repeated elements varied in a controlled way, so the eye moves along with a beat. Spacing might widen and narrow, sizes might alternate large and small, or a shape might change gradually across a row. A magazine that alternates full-page photo spreads with quieter text pages has rhythm across the whole issue, as does a fence whose posts are grouped in twos and threes.
Often confused with Repetition
Rhythm varies its repeated elements to create tempo; repetition keeps every element identical and evenly spaced.
Try this
Arrange ten paper strips evenly, then in groups of two and three, and describe how the pace changes.