On the top part of the neck of the guitar before you reach the headstock is a thing called the "nut". It is usually made of bone or plastic and has notches in it where the guitar strings flow over on their way to the tuning posts.

A capo, when clamped on the neck "moves" the nut to a higher location. It is important for you to understand that the strings still relate to each other in the same way they would without the capo.

Capos are usually used on an acoustic guitar, but are sometimes used on an electric guitar as well. If you have a classical guitar, you will have to get a special capo made especially for that type of guitar because of the wide neck.

There are different styles of capos. There are clamps and wrap-arounds. Choose one that works the best for you, but the clamp kind is the most popular and seems to last longer.

The proper way to use a capo is to place it just above the desired metal fret. Do not put it on the metal fret or below it.

There are three main reasons why you may want to use a capo. One reason is a style issue. This means that you are looking for a certain kind of sound, and you want to use a certain type of chord progression. You just place the capo at the fret you want while making sure that is can still be sung (if it is being sung).

Another reason you would want to use a capo has to do with you not being able to sing it in the original key. If you want to use the same chords, simply place the capo on the fret that would allow you to sing it while using the same chord progression.

You may also want to use a capo to escape having to use bar chords, especially on an acoustic guitar.

So, a capo is just a handy-dandy little tool that can help make things a little easier.