On the guitar many notes of the same pitch repeat in different positions. For example, the following G note can be played in four places.
3rd string, open 4th string, 5th fret 5th string, 10th fret 6th string, 15th fret
This music notation illustrates the complete range of notes on the guitar, using the open position and the first string up to the 19th fret as examples. The diagram, however, illustrates all the possible positions of these notes, covering the entire fretboard.