Perfect Unison
two notes, equal in pitch (0 half steps apart).
Minor Second
two notes, 1 half step apart. e.g. C and D flat/C sharp
Major Second
two notes, 2 half steps apart. They are a whole step apart. e.g. C and D
Minor Third
two notes, 3 half steps apart. e.g. C and E flat/D sharp
Major Third
two notes, 4 half steps apart. e.g. C and E
Perfect Fourth
two notes, 5 half steps apart. e.g. C and F
Augmented Fourth/Diminished Fifth
two notes, 6 half steps apart. This interval is also known as a Tritone because the notes are also 3 whole-tones/steps apart. e.g. C and F sharp/G flat
Perfect Fifth
two notes, 7 half steps apart. e.g. C and G
Minor Sixth
two notes, 8 half steps apart. e.g. C and G sharp/A flat
Major Sixth
two notes, 9 half steps apart. e.g. C and A
Minor Seventh
two notes, 10 half steps apart. e.g. C and A sharp/B flat
Major Seventh
two notes, 11 half steps apart. e.g. C and B
Perfect Octave
two notes, of the same pitch class, one octave apart (12 half steps apart). e.g. C and the next highest C