Musicians commonly use a capo to raise the pitch of a fretted instrument so they can play in a different key using the same fingerings as playing open (i.e., without a capo). In effect, a capo uses a fret of an instrument to effectively create a new nut at a higher note than the instrument's original nut. Capos come in different sizes and shapes for different instruments and fretboard curvatures. Factors that vary by type of capo are ease of use, size, degree of interference with the player's hands, and ability to hold down strings uniformly without affecting tuning. Playing with a capo creates the same musical effect as retuning all strings up the same number of steps. However, using a capo only affects the open note of each string. Every other fret remains unaffected (e.g., the seventh fret of an E-string still plays a B note for any capo position at or below the seventh fret), and thus a performer does not need to adjust for or relearn the entire fretboard as they might with retuning. The scale length of the strings of an instrument affects the timbre of the strings, and thus the use of a capo may alter the tone of the instrument.
