Lesson 6: Half-StepsThis lesson teaches: the half-step, which is the basic unit of pitch distance. You'll need it to understand scales, chords, and melodies.
Before taking this lesson, you should know: the pitch names (Lesson 5: Sharps & Flats).
Pitch distance means: how far one pitch is above (or below) another pitch. We measure pitch distance in half-steps. A half-step is the distance between two pitches that are right next to each other, with no other pitch between them, including the sharps/flats ("black" pitches).
Important: Two pitches that are right next to each other on the piano often do not make a half-step. For example, the white piano keys A and B are "next to each other", but they don't make a half-step, because the black key A♯/B♭ is between them in pitch.
Here are some example half-steps:
A to B♭
B to C: Neighboring white keys do make a half-step if there's no black key between them.
C♯ to D
(By the way, "half-step" is the American term; in the U.K., a semitone is the same thing.)
When you're sure you understand half-steps, go on to Lesson 7: Whole-Steps.