A pyramid is a solid that has the following characteristics.
- It has one base, which is a polygon.
- The vertices of the base are each joined to a point, not in the plane of the base. This point is called the vertex of the pyramid.
- The triangular sides, all of which meet at the vertex, are its lateral faces.
- The segments where the lateral faces intersect are lateral edges.
- The perpendicular segment from the vertex to the plane of the base is the altitude of the pyramid.