Fret buzz is one of the most common complaints we hear, and the good news is that it almost always has a specific, findable cause. Here's a rundown of the usual suspects, roughly in order of how often we see them.

Low action

The most common cause by far. If the strings are sitting very close to the frets, there's less room for them to vibrate before they knock against the fret ahead. Low action is desirable for playability, but there's a point where it's simply too low for the guitar to stay buzz-free.

Insufficient relief

The neck needs a small amount of forward curve to give the strings enough clearance in the middle of the neck. If the truss rod has been adjusted too straight, or the neck has shifted due to humidity, buzzing often shows up around the middle frets first.

Worn or uneven frets

If one fret is slightly higher than its neighbours, whether from wear or an original inconsistency, the string will buzz against it before it reaches the fret you're actually pressing. This kind of buzz tends to be localised to a specific area of the neck rather than happening everywhere.

A loose or worn nut or saddle

A nut slot cut too low, or a saddle sitting too low, can cause open-string buzz specifically, since it changes the string's height right at the very start of its vibrating length.

Loose hardware

Sometimes it's not the strings buzzing at all. A loose tuning peg, an unsecured strap button, or even a rattling truss rod cover can produce a buzzing sound that sounds like it's coming from the strings but isn't. It's worth ruling this out before assuming it's a setup issue.

Your playing technique

Sometimes buzz is simply a matter of how firmly and where you're fretting a note. Pressing too close to the fret itself, rather than just behind it, or not applying quite enough pressure, can cause buzzing on a guitar that's otherwise perfectly set up.

Working out which it is

If the buzz happens on every string across most of the neck, it's likely an action or relief issue. If it's isolated to a specific fret or area, it's more likely a fret problem. If it only happens on open strings, look at the nut. And if it moves around depending on how you're fretting, it might simply be technique.

Getting it sorted

Most buzzing is fixed through a proper setup: adjusting truss rod relief, nut and saddle height, and checking the frets for consistency. It's rarely something to worry about, and it's usually a quick job for a guitar tech to sort out properly.