CalcPlot3D is a java applet that illustrates many multivariable calculus concepts. The applet itself is located at http://web.monroecc.edu/manila/webfiles/ calcNSF/JavaCode/CalcPlot3D.htm. This entry describes an article in Loci: Resources about the applet with extensive discussion of how it can be used to illustrate dot and cross products, motion in the plane and in space, the TNB-frame, the osculating circle, surfaces, level surfaces, partial derivatives, gradients, Lagrange multiplier optimization, defining the limits of integration for double and triple integrals, parametric surfaces, vector fields, and line integrals.