X

x = Don't play that string. In some cases, one may need to mute the xed string.

(I'm a little disappointed here. I though maybe this would be a thread on the band named X!)

I clicked it because it sounded very mysterious.

x
x
x
x
x
x

^That can mean to deaden the strings, to get a kind of percussive effect.

x marks the spot not to be touched

I think in TAB an x means to lightly touch the string with your fretting hand to create a percussive sound when picking it.

I think in TAB an x means to lightly touch the string with your fretting hand to create a percussive sound when picking it.

It can mean either. It might indicate palm muting a power chord for percussive sound. It might also mean muting the string very heavily when you play an octave. That's the kind of thing you'll see in tab. If you see an "x" in a chord symbol, it would mean not to play the string.

Check How do you read and write tab for a good explanation of the various symbols used in tab.

Right -- My comments apply to chord charts ("static" TAB).

I though maybe this would be a thread on the band named X!)
Billy Zoom, yeah! Ah, I remember seeing X at the Roxy in L.A., all those years ago... makes me feel old. Think I'll go play that Chuck Berry riff from "Johny Hit and Run Pauline" now ... 8)