A capo is simply a device that bolts down on the neck at any given fret to allow you to play chords using open strings in different keys. An open string is simply a string that you don't need to put a finger on and just rings until it dies out. Normally the only open strings are those at the nut ( that plastic or bone bit that all the strings go over ) at the head of a guitar. But a capo is really just a way of moving a nut to any fret along the neck.

Open strings don't cut off like fingered strings can and just ring on like you would hear in folk songs .... versus jazz or rock guitar where the chords are made using fingers on all strings so can be cut off rhythmically by simply lifting the fingers slightly to stop the strings vibrating.



[This message has been edited by Nigel (edited 03-20-2008).]