What is the nut on a guitar?
The nut is the small strip at the top of the neck that holds the strings in place and sets their starting height. The strings rest in shallow grooves cut into it, which keeps them spaced evenly and sets how high they sit above the first fret.
The nut marks the starting point of the open string at the head of the guitar (end of the fretboard). When you play a string without pressing down anywhere on the neck, you're hearing it ring between the nut and the bridge at the other end of the guitar (usually in the middle of the body). Every fret position is measured from the nut up the fretboard.
On a chord diagram
When chord diagrams show a chord that is within the first 4 frets, the nut is indicated by a thick line. That line represents the nut, not a fret.
Here's how it looks on a chord diagram for an A chord starting at the nut.
When chord diagrams show a chord that isn't within the first 4 frets, that first line is regular size to indicate that there is no nut there and it's a regular fret. To indicate where on the neck you should play this chord, there is a "5fr" which means "5th fret."
Here's how it looks on a chord diagram for an A chord starting at the 5th fret.
Related glossary terms
- Fret - divide up the guitar freboard into sections for easy reference and playing
- Capo - acts as a temporary and movable version of the nut
- How do I read a guitar chord diagram? - explains how the nut is shown on a diagram