Regular Polyhedrons

When each face of the polyhedron is identical it is called a regular polyhedron.
All its faces must be congruent,
All its edges must be equal,
All its vertices (corners) must be congruent

Tetrahedron

4 triangular sides

Cube

6 square sides

Octahedron

8 triangular sides

Dodecahedron

12 pentagonal sides

Icosahedron

20 triangular sides