A capo is a device you put on the neck of your guitar to raise the pitch and change the key. This is great for playing a song in a different key to suit your voice. The other great thing is, if you are playing with another person, and say they are playing in the key of C. You can put the capo on the 3^rd fret and play an A chord or you can put it on the 5^th fret and play a G chord. It makes things sound very lush and interesting, technically it’s the same chords, but different inversions. You can see from the charts below, where you should put the capo to get the desired results.