The Beat is the regularly occurring pattern of rhythmic stresses in music. When we count, tap or clap along with music we are experiencing the Beat. Try tapping your finger along with different types of music and see what happens.
Tempo is the speed of the Beat, usually expressed in Beats Per Minute (BPM). For example, at 120 BPM there will be 120 beats in one minute. Tempo can also be expressed verbally with different music terms, such as Slowly, Fast, Allegro, or Largo.
If you have a metronome try different settings and tap along. If you don't have a metronome, find a clock that shows seconds. If you tap along with the seconds you are experiencing 60 BPM because there are 60 seconds/beats per minute.
