Nets are two-dimensional representations of three-dimensional shapes. German painter Albrecht Dürer (1471–1536) probably had fishing nets in mind when he first used the term net to name these two-dimensional figures that may be "folded" to form three-dimensional solids. Some of the nets of a cube are shown in the figure below. Although they are each formed with six squares, they are different nets of a cube.

Each of these nets may be folded along its edges to form a cube.

Any solid with polygons for faces, called a polyhedron, may be unfolded to form a net. The polyhedron known as a square pyramid has several different nets. Some of them are shown below. Each of these nets can be folded up to form a square pyramid.

Nets are used to study the properties of various polyhedrons. A more valuable use of nets is in the field of networks...