The distance between two pitches is called an interval. When identifying intervals, the generic interval must be established first, which names how far apart the pitch classes are but ignores accidentals (flats, sharps, and naturals.)
Intervals are named with ordinals ("first, second, third"), not integers ("one, two, three.") Since there is no ordinal for zero, it is important to remember to count both the pitch from which you are starting and the pitch where you end.
Thus, two notes of the same pitch class are a "first" apart, although there is a special name for this called a unison (from "uni-" meaning "one.") Notes that are adjacent to each other on the staff or in the alphabet are a second apart, and so on until we get to an "eighth," which also has a special name, octave.
It does not matter what two pitches are involved: count the first one, go up through the alphabet adding an ordinal each time, and count the note you end on.
The generic interval must be established before you can name specific or harmonic intervals, which we will learn about later.
.jpg)