Learning to play the guitar can be similar to using a camera. With a camera there are buttons you hit to do different things, like to adjust light, to zoom in or out, to add different frames, to take pictures. At the end of using all these buttons you will have one finish product and that is a picture. Likewise with a guitar there are more than one string, ease string has different function; that is different key. These different strings a strum simultaneous, but the finish product of hitting these strings is a note. Both the hollow body guitar musicians friend have different uses but one function.