Pinch Harmonic

A pinch harmonic is a guitar technique to achieve artificial harmonics in which the player’s thumb or index finger on the picking hand slightly catches the string after it is picked, canceling the fundamental frequency of the string, and letting one of the overtones dominate. This results in a high-pitched sound which is particularly discernible on an electrically amplified guitar as a “squeal”.

Billy Gibbons of ZZ Top is a great example of a player who uses pinch harmonics a lot.