120 BPM METRONOME

120 Beats per Minute Metronome click with beats and 4/4 bars counting.
Allegro -- fast, quickly and bright (109--132 BPM)

Allegretto -- moderately quick (98--109 BPM)
Vivace -- lively and fast (132-140 BPM) (quicker than allegro)

Beats per minute (BPM) is a unit typically used as a measure of tempo in music and heart rate.
The BPM tempo of a piece of music is conventionally shown in its score as a metronome mark, as illustrated to the right. This indicates that there should be 120 crotchet beats (quarter notes) per minute. In simple time signatures it is conventional to show the tempo in terms of the note duration on the bottom. So a 4/4 would show a crotchet (or quarter note), as above, while a 2/2 would show a minim (or half note).
In compound time signatures the beat consists of three note durations (so there are 3 quavers (eighth notes) per beat in a 6/8 time signature), so a dotted form of the next note duration up is used. The most common compound signatures: 6/8, 9/8, and 12/8, therefore use a dotted crotchet (dotted quarter note) to indicate their BPM.
Exotic time and particularly slow time signatures may indicate their BPM tempo using other note durations. BPM became common terminology in disco because of its usefulness to DJs, and remain important in the same genre and other dance music.