The term polyhedron is the one used to designate those three-dimensional geometric figures that are composed of several faces or facets. It can be said that the polyhedron is the equivalent of polygons, flat geometric figures with many sides but without three-dimensionality. The name of polyhedron comes from the Greek language for which poli means "many" and edro or edron means "faces".
Polyhedra are much more visually striking than a polygon. This has to do with the fact that they gain three-dimensionality and, therefore, their surface becomes much more complex. The elements that normally make up a polyhedron are three, some of them equivalent to those of the polygon: the faces, the edges and the vertices. The faces are the planes that are formed along the surface of the polyhedron and that can be very numerous depending on the polyhedron in question. Then the edges or lines that delimit the planes between themselves and that can be shared by two planes together continue. Finally, the vertices, as in the polygon, are the point of union of two or more edges as well as of two or more planes.
Polyhedra, as might be expected, are complex figures that can be grouped into two main sets: regular and irregular polyhedra. While the former are characterized by being composed of faces and vertices equal to each other, the irregular ones are a composition of faces and vertices of different size and level, which is why their final view is much more impressive and messy. Among the former, the regular polyhedra, we find, for example, cubes. In the group of irregular polyhedra one of the best known forms is the prism in all its variants as well as the figures that bear the name "truncated" together with the number of faces they have (for example the truncated tetrahedron).
