A compass is a drawing instrument used for drawing circles and
It has two legs, one with a point and the other with a pencil or lead.
You can adjust the distance between the point and the pencil and that setting will remain until you change it.
Along with a straightedge, the compass is used extensively in constructions, where geometric operations are carried out by drawing only, with no calculations involved.
See Constructions using a straightedge and compass
This kind of compass has nothing to do with the magnetic compass used find the north direction when you are lost.
(C) 2011 Copyright Math Open Reference. All rights reserved