NUMBERING THE FRETS
The Frets, or pieces of metal running across the guitar neck separate notes on the guitar from each other. When we press down on the guitar, we press on the wood between the two frets to play each note. Each fret is numbered from the 1st fret closest to the headstock (the largest fret), and run up to between 19 and 24 frets (the smallest fret) depending on the design of your instrument.
The markers on the fingerboard are to help you locate the correct fret when playing. These markings can vary from one guitar to another but are always found on the 5th, 7th, 9th, and 12th frets as well as on the side of the neck facing the player in order to make these frets easier to locate.
Guitar Fingerboard with Numbered Frets.

