Perfect Interval
The interval between the keynote of a major scale and the unison, 4th, 5th or octave of that scale
Major Interval
The interval between the keynote of a major scale and the 2nd, 3rd, 6th or 7th of that scale
Diatonic Interval
When the keynote and the upper note of an interval are from the same major scale
All diatonic intervals in the major scale are either [ ] or [ ].
Perfect or Major
Minor Interval
When the interval between the two notes of a major interval are decreased by a half step
[ ] Intervals can not be made minor
perfect
Augmented Interval
When a perfect or major interval is made larger by a half step
To raise a sharp note by a half step, use a [ ]
Double Sharp
Diminished Interval
When a perfect or minor interval is made smaller by a half step
To lower a flat note by a half step, use a [ ].
Double flat
Chromatic Interval
When the keynote and the upper note of an interval are not from the same major scale
[ ], [ ], and [ ] intervals are always chromatic intervals in major keys.
Minor Diminished Augmented
Transposition
When a melody is rewritten with the exact same sequence of notes and intervals into another key
Why use transposition?
This raises or lowers the notes to make a melody easier to sing or play, or so it can be played by an instrument in another key.