Getting to Know the Notes on a Guitar Fretboard
Guitar players must know the notes on the fretboard to keep track of the specific scale patterns and chords they play all over the neck. But rather than memorize every single note in every fret on every string, guitarists do better to just know the natural notes along the 6th and 5th strings. After all, most scale patterns and chord shapes are rooted on these strings. Octave shapes can be used to track other notes in other positions.
The following fretboard diagram shows you the notes along the 6th and 5th strings.