What is a mathematical tool that is used to construct circles?

A compass is a mathematical tool commonly used to construct circles. It consists of two arms: one with a pointed end for the center of the circle and the other with a pencil for drawing the arc. By placing the pointed end at a specific point and adjusting the distance between the arms, a circle of a desired radius can be accurately drawn. Additionally, a straightedge can be used in conjunction with a compass to help define diameters or chords.