A multi-neck guitar is a guitar that has multiple fingerboard necks. They exist in both electric and acoustic versions. Although multi-neck guitars are quite common today, they are not a modern invention. Examples of multi-neck guitars and lutes go back at least to the Renaissance.
Today, the most common type of multi-neck guitar is the double neck guitar, of which the most common version is an electric guitar with twelve strings on the upper neck, while the lower neck has the normal six. Combination six-string and bass guitar are also used, as well as a fretless guitar with a regular fretted guitar, or any other combination of guitar neck and pickup styles. There are also acoustic versions. Two necks allows the guitarist to switch quickly and easily between guitar sounds without taking the time to change guitars.