So what is a capo? Well a capo is a devise that attaches to the neck of the guitar and is used to shorten the length of the strings, which will in turn raise the pitch of each open string.

Jim Dunlop Trigger Capo

Capos are used to enable guitar players to play songs in a different key to which they were written. They want to do this for a number of different reasons. When playing with a band it makes it easier to play in the same key as the other instruments (piano etc) without playing complicated chords. It is also often used to change the songs key so that the plyaer is able to sing to song comfortablly without it being too high or too low.

Basically the Capo is placed at the required fret at the bottom of the fret just above the fret wire. The Capo forms a barre across all strings and effectively acts as the nut of the guitar, but a nut that can be moved up or down the neck. For each fret up (thats up in pitch/down from the  nut) the capo is moved the chords move up half a step. So a Capo on the 2nd fret is 1 step up, this takes an A chord to a Bb or a D chord to a Eb. See the table below for more translations.

It is really simple to use a capo and can be very helpful for a beginner. Try it yourself, take a simple song you know put the capo on the 2nd fret (or any other) and play the chords exactly the same but below the capo. The song is now in a new key.

Capos come in different styles, a strap on style and a trigger style as in the pictue above. They are both easy to use but a trigger capo is very quick and very easy, just squeeze it and put it were you want it.