Enter the equation of the graph in parametric form and press the Graph it! button. Or select a sample curve from the list at the bottom right.
The variable 't' must always be used as the parameter. If you want to see a graph expressed in the normal functional form (y = f(x)), just enter x = t, y = f(t). All of the common mathematical functions are supported: trig, hyperbolic trig, sqrt, floor, ceil, abs, etc. For exponentiation, the '^' symbol may be used (e.g. 2^4 = 2*2*2*2).
The applet can show multiple curves simultaneously - just unset the Automatic clear toggle. With the Preserve aspect ration button set, the same scale is used for x and y; when it is not set, the scales are set so that the curve fills the window.