A cube is a solid in three dimensions, with three mutually perpendicular right angles evident at the vertices. In this article, the author describes how to create a four-dimensional cube. Before searching this extra dimension, she first reviews what people know about zero, one, two, and three dimensions, and certain shapes in each of these. She then provides a recipe for building what she is trying to describe: instructions for making a (three-dimensional representation of a) tesseract or hypercube, or the four-dimensional equivalent of a cube. "Hypercube" is the more general term and applies in dimensions higher than three; the word tesseract is usually reserved for the specific four-dimensional case. (Contains 10 figures.)