The distance between two musical pitches is called an interval. Intervals
either melodic (sounded separately as in
a melody) or harmonic (sounded together,
Every interval description has two parts:
Quantity describes a numeric value, like
a 2nd, 3rd, 4th, 5th, etc.
Quality describes differences within numeric
Major, minor, augmented, diminished, or perfect.
All of the intervals above the first note (or tonic) of a major scale
are either Major or Perfect. (See example below).
2nd, 3rd, 6th, and 7th's above the tonic are major.
4th, 5th, 8ve (octave), and 1 (unison) are perfect.