You have to learn the musical alphabet to understand guitar theory.
There are 12 total notes in the musical alphabet in Western harmony.
This is the musical alphabet in order from C to B:
| C | C# | D | D# | E | F | F# | G | G# | A | A# | B |
You’ll see two types of notes here: Natural notes and accidental notes.
What is a natural note?
A natural note has no sharp or flat.
There are 7 natural notes: C-D-E-F-G-A-B.
What is an accidental note?
An accidental note has a sharp or flat, such as G# or Bb. Accidentals appear between natural notes.
There are only 2 notes without a sharp: B and E. This means that there’s only 1 half-step between them and the next natural note. You can notice this when you look at a piano, and see that there’s no black piano key between B and C or E and F.
What’s next?
Now you can learn how to play the natural notes on each string of the guitar.