So I have been playing the electric guitar for awhile now and I just found this technique I wanted to learn, but I have no idea where to begin, I saw(and heard) it in this video below


It occurs at 1:21, 1:24, 1:27, 1:30, 1:33, and 1:36. The high-pitched sound is what I'm looking for. It kind of looks like she's slapping the the strings(pinch harmonic?) but I'm a novice and not familiar with this technique. Can anyone help me?
That's feedback. Fuzzy, hollow-body-guitar, high-volume, probably a trashy amp... it's not a technique at all really. It's a function of the gear they're using, the volume they're playing at, and physics.
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As said, it's not a technique but it can be learned and incorporated i reckon.

To achieve this, put your amp on the OD setting and hold your guitar right next to it, facing the speaker. Should give you some feedback and if you play with it you might be able to incorporate it musically, although off the top of my head i can't think of anyone who does.