This command inserts a tempo designation at the insertion point. The tempo is designated in units of time base beats per minute. You control both the time base (quarter notes, eighth notes, half notes, or their dotted variations) and the beats per minute in that time base. This controls the speed at which a song plays back. The larger the tempo, the faster the song will play.
When using a tempo base smaller than a quarter note (8th and dotted 8th), not all values will result in unique play back tempos, due to internal rounding issues.
It is usually best if tempo changes are designated in only one staff of a score, thus making it easier to keep track of where the tempo changes occur.
You can also add an additional expression text to a tempo to humanize the tempo instruction. The expression text does not influence the tempo in any way, as the numeric tempo designation is used exclusively for this purpose.