Explore torus types, torus knots, and their topology — drag to rotate
A torus is a surface of revolution: a circle of radius r centered at distance R from the axis. When R > r: ring torus; R = r: horn torus (self-intersects at origin); R < r: spindle torus. A torus knot T(p,q) winds p times around the torus longitudinally and q times meridionally. T(2,3) is the trefoil knot.