What does an octahedron look like?

An octahedron is a polyhedron with eight faces. A regular octahedron can be composed of eight equilateral triangles, four forming each half, and meeting in the middle at a square.

Imagine a pyramid, with a square base. Rising up from each edge is an equilateral triangle that meets the other four triangles at the apex. Now, turn the pyramid over and add four more triangles to the other side the same way. You now have an octahedron.

For more information, and a rotating picture, please see the related link below.