A guitar pick is a plectrum used for guitars. Picks are generally
made of one uniform material—such as some kind of plastic (nylon,
Delrin, celluloid), rubber, felt, tortoiseshell, wood, metal,
glass, tagua, or stone. They are often shaped in an acute
isosceles triangle with the two equal corners rounded and the
third corner less rounded. They are used to strum chords or to
sound individual notes on a guitar.