The Musical Alphabet

All of western music uses twelve notes. That is the entire supply. After the twelfth they start again, higher, with the same names.

The names run A B C D E F G, and then back to A. That is only seven letters for twelve notes, so five of them are named by borrowing: a sharp raises a note by the smallest distance available, a flat lowers it by the same. The note between A and B is either A sharp or B flat depending on which neighbour you are counting from, and it is one note with two names.

That smallest distance is called a half step. On a guitar it is one fret. Two frets is a whole step.

Now the part that trips everyone up: the pattern is not even. Between most letters there is a whole step, but between E and F, and between B and C, there is only a half step — those pairs are already touching, with nothing between them. This is why there is no E sharp and no B sharp in the ordinary run of notes, and it is not an arbitrary rule. It is the reason the piano has black keys in groups of two and three instead of one between every white key.

Digital Keyboard

Find the two white keys with no black key between them — that is E and F. Then find the other pair: B and C. Everywhere else, there is a black key in the gap.

On a guitar the same fact is easier to see, because every fret is a half step and nothing is hidden. Play the low E string one fret at a time and you walk through all twelve notes in order.

Every note on the low E string, one fret at a time

Twelve half steps and you are back to E, an octave higher. Notice E to F is one fret, and B to C is one fret, while the rest are two.

e
B
G
D
A
E

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Knowing which note you are on is not trivia — it is what lets you find a chord or a scale anywhere instead of only where you memorised the shape.

The trainer below drills exactly that. Two minutes a day beats an hour once.

Fretboard Note Trainer

Start with the bottom two strings only. Those are where chord roots live, so they pay off first.