The Musical Alphabet

The different pitches in music are named with corresponding letters. This musical alphabet ranges from A to G, and then repeats itself, infinitely above and beneath, our range of hearing.
These letters from A to G are called natural notes. The musical alphabet differs however
from the ABC’s we learned in school, by adding the concept of sharps, and flats.
Sharps and flats occur between the natural notes. A sharp is introduced when a natural note is raised by a half step, while the flat occurs when a natural note is brought down a half step.

Dot System

The fretboard of a bass guitar will typically have dots located at specific frets on the neck. The 3rd, 5th, 7th, 9th and 12th frets. (Some guitars have a marker at the first fret, like the bass I own)
The purpose of having dots on the fretboard is to assist bassists in locating the positions and notes to play. The 12th fret marker is also a significant
marker because, at the twelth fret the note is the same as if the open string.