Tempo
Tempo is defined as the speed of a song. It is measured in beats per minute. A very fast temple has about 200 – 208 beats per minute. A moderate speed tempo has about 108-120 beats per minute. Very slow tempo has 40 – 60 beats per minute.
Measures (Bars)
In music theory, these beats are grouped into bars (British English) or measures (American English). Each measure has the same amount of beats. Bar line is vertical bar that separates each measure on a musical staff. A double bar lines are two vertical lines used to separate different music sections or to mark the end of a piece of music.
Time Signature
Time signature on a musical staff defines how many beats in a measure (top number) and the note type that gets one beat (bottom number). The time signature is written at the beginning of a staff after the key signatures.
Top number defines the number of beats in a measure.
Bottom number defines the type of notes that gets one beat.
The Common Time Signature
4/4 Time Signature is also called the common time, because it is the most common time signature in modern music.
4/4 Time Signature
Top number: Four beats per measure
Bottom number: Quarter note gets one beat
A half note gets two beats.
A whole note gets four beats.
A quarter rest gets one beat and a half rest gets two beats.
A whole rest gets four beats.
3/4 Time Signature
Top number: Three beats per measure
Bottom number: Quarter note gets one beat
A half note gets two beats.
A dotted half note gets three beats.
An eighth note gets half a beat.
A sixteenth note gets a quarter of a beat. (It takes two eighth notes or four sixteenth notes to get one beat.)
Piano Music Theory 