How can I use a capo to change keys while playing the guitar?

A capo is a device that you can place on the neck of the guitar to change the key of the music you are playing. By placing the capo on a specific fret, you can effectively raise the pitch of all the strings, allowing you to play in a higher key without changing the chord shapes you use. This can be useful for adjusting the key of a song to better suit your voice or to make it easier to play certain chords.