Rhythm is a way to imply movement through repetition. If the rhythm is regular it will repeat at a predictable interval. Imagine a pebble dropped in a lake. The concentric circles that are created are regular. If the rhythm is irregular it will repeat at less predictable intervals. Waves crashing on a beach creates a rhythm but not one that occurs in a predictable manner. Rhythm is also an important component of pattern and motif.
Rhythm in serial works also relies on repetition whether it is the repetition of visual elements within a set or costume, the repetition of phrases or ideas in the dialogue, repetition of elements in a film, such as transitions, camera angles, or use of montages.
Although rhythm in music shares the same basic concepts as the visual arts the application is somewhat different.
Rhythm is also a way for works of art to create more unity and/or continuity.