Guitarists use guitar note charts to know the names of the notes on each string, to understand the formation of chords and to read guitar tablature. Chord charts and tablature are two different but closely related ways to read note arrangements.
In the most basic sense, a note chart allows guitarists to read and memorize the names of all the notes on each string. Each individual fret on each string is its own note, and these notes get higher as they move up the neck of the guitar. Knowing the names of the notes allows guitarists to move scales or chords to different starting notes.
Guitar charts are also used to indicate chord formations. Also known as chord boxes, these visual representations of the guitar neck indicate which fingers need to be placed on which frets to play specific chords. Many common chords use the first four frets closest to the neck of the guitar, but chord charts can also indicate when a chord if formed on higher frets.
Tablature is commonly used to write out songs and compositions for guitar. Tabs are simpler than actual written music, and they often do not indicate time or rhythm. They can, however, indicate all of the notes that are played throughout a song. Tablature shows which frets need to be played through the use of numbers arranged on the different strings.