Though a guitar may be played on its own, there are a variety of common accessories used for holding and playing the guitar.
Capotasto
A capodastra (or capo, cejilla in Spanish) is used to change the pitch of open strings. Capos are clipped onto the fret board with the aid of spring tension, or in some models, elastic tension. To raise the guitar's pitch by one semitone, the player would clip the capo onto the fret board just below the first fret. Their use allows a player to play in different keys without having to change the chord formations they use. Because of the ease with which they allow guitar players to change keys, they are sometimes referred to as "cheaters". Classical performers are known to use them to enable modern instruments to match the pitch of historical instruments such as the renaissance lute.
Slides
A slide, (neck of a bottle, knife blade or round metal bar) used in blues and rock to create a glissando or 'hawaiian' effect. The necks of bottles were often used in blues and country music. Modern slides are constructed of glass, plastic, ceramic, chrome, brass or steel, depending on the weight and tone desired. An instrument that is played exclusively in this manner, (using a metal bar) is called a steel guitar or pedal steel. Slide playing to this day is very popular in blues music and country music. Some slide players use a so called Dobro guitar.
Some performers that have become famous for playing slide are George Harrison, Bonnie Raitt, Derek Trucks, Warren Haynes, Duane Allman, Muddy Waters and Rory Gallagher.
Plectrum
A "guitar pick" or "plectrum" is a small piece of hard material which is generally held between the thumb and first finger of the picking hand and is used to "pick" the strings. Though most classical players pick solely with their fingers, the "pick" is still often used for electric and some acoustic guitars. Though today they are mainly plastic, variations do exist, such as bone, wood, steel or tortoise shell. Tortoise shell was the most commonly used material in the early days of pick making but as tortoises became more and more endangered, the practice of using their shells for picks or anything else was banned. Tortoise shell picks are often coveted for a supposedly superior tone and ease of use.
Picks come in many shapes and sizes. Picks vary from the small jazz pick to the large bass pick. The thickness of the pick often determines its use. A thinner pick (between .2 and .5 mm) is usually used for strumming or rhythm playing, whereas thicker picks (between .7 and 1.5+ mm) are usually used for single-note lines or lead playing. The distinctive guitar sound of Billy Gibbons is attributed to using a quarter or peso as a pick. Similarly, Brian May is known to use a sixpence coin as a pick.
Thumb picks and finger picks that attach to the finger tips are sometimes employed in finger-picking styles.