A guitar pick is a type of plectrum designed for use on a guitar. Over time people have made picks of various materials, including nylon, plastic, rubber, felt, tortoiseshell, metal, and stone. The most often take the shape of an acute isosceles triangle with the two equal corners very rounded and the acute corner rounded to a lesser degree. This shape is, however one of many used by manufacturers.

Guitar picks come in varying thicknesses to accommodate the different playing styles and kinds of strings. Thinner plectrums are more flexible and tend to offer a wider range of sounds, from soft to loud, and produce a "click" that emphasizes the attack of the picking. However, some argue that heavier picks produce a brighter tone. Whether there is truth in either judgement is up to the individual's opinion, and the choice is entirely a matter of personal preference.

Picks will normally have small protusions to make them easier to keep hold of if the fingers start to sweat (very common on stage due to the hot lights). Some picks (as illustrated) will have a high-friction coating to help the player hold on to them. The small perforations in the stainless steel pick serve the same function. Many players will often have spare picks attached to a microphone stand.

Picks made out of steel will produce a much brighter sound than plastic ones. They do however wear the strings quickly and can easily damage the finish on the guitar if used for strumming - especially on acoustic guitars.

The equillateral pick can often be much easier for beginners to hold.

The shark's fin pick can be used in two ways - normally employing the blunt end or the small perturbations can be raked across the strings producing a much fuller chord.

Bass players who use a pick will normally use much heavier (thicker) picks than guitar players. Many bass players find that coins make excellent picks.