Defined by movement and experienced only in time, music and dance are truly ephemeral. Whether the art form is a three minute pop song or a two hour ballet, it cannot be performed without a clock and it cannot be perceived outside of the cradle of time. Tempo, beat, and pulse are terms musicians routinely use to establish the time of a composition.
Since the Baroque period, musicians have developed a lexicon of Italian words to set the approximate tempo of music. No fewer than twenty-eight terms are used in an effort to get musicians to play music at the tempos intended by composers.