What is a Capo / Guitar Capo.. ?

A capo or capotasto [kapoˈtasto], Italian for “head of fretboard” is a device musicians use on the neck of a stringed (typically fretted) instrument to shorten the playable length of the strings..(In laymen’s terms it changes the pitch of the notes to ones preference!!). It is a common tool amongst guitarists and the earliest known use of  Capo or .. capotasto ( Capotasto [kapoˈtasto], Italian for “head of fretboard”) is by Giovanni Battista Doni who, in his Annotazioni of 1640, used it to describe the nut of a viola da gamba although oddly enough the first patented capo was designed by James Ashborn of Wolcottville, Connecticut.

Musicians commonly capo to adjust the pitch of a fretted instrument to their own preference so they can play in a different key using the same chords as open ones(i.e., without a capo).