Those that have Rhythm, know Rhythm as the most subtle of pleasures.
Rhythm from Greek 'rhuthmos', derived from rhein 'to flow'
is in its most general sense the ordered alternation of contrasting elements.
The notion of rhythm occurs in the arts (e.g. poetry, paintings, architecture and music). But unlike paintings and sculptures, which are compositions made in space, music is a composition dependent upon time. In music, rhythm is the music's pattern in time. It is an indispensable element of all music. Rhythm can exist without melody, as in the drumbeats of primitive music, but melody cannot exist without rhythm.
Attempts to define rhythm in music have produced much disagreement, partly because rhythm has often been identified with one or more of its constituent, but not wholly separate elements, such as accent, tempo and metre.
Rhythm is however not limited to music or even the arts. It can also be found in nature; e.g. biological rhythm, where it is again dependent upon time.