Polyhedrons come in all shapes and sizes. Anything that has multiple faces joined at their edges can be a polyhedron. Picture Earth as a six-sided cube. Or as a triangular pyramid with four faces ...

A 3D shape with all straight edges and flat faces is a polyhedron. Other 3D shapes with least one curved surface are not polyhedra. A 3D shape with regular polygonal faces, meeting at equal angles, is ...