A guitar pick is a plectrum used for guitars. A pick is generally made of one uniform material; examples include plastic, nylon, rubber, felt,tortoiseshell, wood, metal, glass, and stone. They are often shaped in an acute isosceles triangle with the two equal corners rounded and the third corner rounded to a lesser extent.
The capo is most commonly used to raise the pitch of a fretted instrument so that a player can perform a piece in a certain key using different fingerings than they would use if played "open" (i.e. without a capo). In effect, a capo uses a fret of an instrument to create a new nut at a higher note than the instrument's actual nut.
A guitar amplifier (or guitar amp) is an electronic amplifier designed to make the signal of an electric or acoustic guitar louder so that it will produce sound through a loudspeaker. Most guitar amplifiers can also modify the instrument's tone by emphasizing or de-emphasizing certain frequencies and adding electronic effects.
