Pick slide
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A pick slide or pick scrape is a guitar technique most often performed in the rock or metal music genres. The technique is executed by holding the edge of the pick against the any of the three or four wound strings and moving it along the string. As the pick moves across the string, the edge of the pick catches the string's windings in rapid succession causing the string to vibrate and produce a note. This rapid rattling of the pick's edge against the windings also gives the resulting note a grinding or grating quality. The pitch of a pick slide rises as the pick moves closer to the bridge, nut or fret (if the string is being fretted) and lowers as the pick moves away from these points, towards the center of the vibrating length of the string. Since pick slides usually start near the bridge and end over the higher frets, the notes have a characteristic of gradually lowering the pitch. This technique is most effective for the electric guitar. It isn't loud enough to be distinguishable from ordinary fret noise on an acoustic guitar.
It is not bad in any way for the amp, guitar or strings. But it IS bad for the pick, as it will ruin it after a while.