The dodecahedron is a regular 12-faced polyhedron. Each face is a pentagon, which is a regular 5-sided polygon. "Regular" means that all similar parts in the form are the same, such as angles or length of an edge. The dodecahedron is the inverse of the icosahedron (Figure by R. Buckminster Fuller). That is, if you connect dots from the center of each face, you draw the opposite form. The dodecahedron has 20 vertices. It is important for Buckminster Fuller's geodesic geometry.