Lesson 7: Half-StepsTo learn about chords and melodies, you will need to know scales; and to learn scales, you need to understand half-steps. You need to know the pitch names for this lesson; if you don't know them, then first go back to our pitch lessons: Lesson 4: Pitch Names, Lesson 5: Letters Game, and Lesson 6: Sharps & Flats.
We use half-steps to measure pitch distance: how far one pitch is above (or below) another pitch. The half-step is the smallest possible distance between two different named pitches; it means two pitches that are right next to each other in the "pitch ladder" (see Lesson 3: Pitch & Keyboard), without any other pitches (neither black nor white) between them.
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 "physically" next to each other on the piano, 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: Some neighboring white keys do make a half-step.
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 8: Whole-Steps.