A cycloid is a curve generated when a circle rolls along a straight line without slipping. The document provides step-by-step instructions to draw a cycloid curve by marking points along the circumference of a rolling circle and connecting those points to form the curve. First, a circle is divided into 12 equal parts and a line is drawn that is the length of the circle's circumference. Corresponding points on the circle and line are then connected to create the curved shape of a cycloid.