Nut Slot

A groove or indentation in the top surface of a guitar, bass, or other instrument’s nut that serves to hold the strings in their proper places at the peghead end of the neck (the bridge serves the same function on the body end of the guitar). The depth of the nut slots determines the string height at the first fret. The nut slot needs to be cut or filed at the proper position, and angle, and with the proper depth and width, in order for the string to vibrate and move as freely as possible, yet not pop out of the nut when the string is bent or finger vibrato is added.