Vintage Gretsches, 2015 Gibson Les Pauls, and some other guitars feature a “zero fret” in the location where the nut is normally placed at the headstock end of the fretboard. The zero fret sets the height of the string over the fingerboard when the string is played “open” (without being fretted), and the nut, placed behind the zero fret simply sets the string spacing for the strings before they route to the tuners on the headstock.
Is there an advantage to having a zero fret in place of a nut? And if there is, why doesn’t every guitar have one? As with many such questions, the answer is somewhat “fact” based and somewhat subjective. There are both advantages and disadvantages to a zero fret.
On the positive side, proponents feel that a zero fret matches the tone and sustain of an open string more closely to that of a fretted note. Since the strings sit on top of the zero fret, any gauge of string can be used without recutting or replacing the nut. Also, with a zero fret the chance of “string clamping” — where a string sticks in the nut when being tuned — is greatly reduced (we’ve all heard the characteristic “ping” when a stuck string lets loose after being stuck while tuning) and a zero fret can make fine tuning easier.
However, there can also be drawbacks to having a zero fret. A zero fret wears differently than a nut over time. When the zero fret starts wearing, it can interfere with string bending. Adjusting the action of a zero fret is more difficult, and replacing a worn zero fret is basically the same as replacing a low fret, as opposed to popping off a traditional nut and gluing a new one in its place.
Some players observe that there is a “feel” difference with a zero fret — some like it, some prefer a traditional nut.
This all adds up to a zero fret being different than traditional nut; whether it’s better or worse depends on the player and the guitar. Try them both, and play what feels best to you!