Putting a capo on a guitar neck shortens the length of the strings, which raises the pitch and transposes the guitar to a different key. This allows guitarists to use familiar open-position chord shapes in keys where they would otherwise not be an option. Capos are useful for beginners who haven’t learned barre chords or anyone who prefers the ringing sound of open strings in alternate keys.
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The capo is commonly used by singer-songwriters who want to use lush, open chords in a key suitable for their voice. It’s also a great studio tool to create unique guitar sounds through open-string parts higher up the neck. Blues guitarists like Albert Collins and Jimmie Vaughan also use the capo in lead guitar playing to unlock open pentatonic licks in various keys.