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.