Prisms are solids (three-dimensional figures) that, unlike planar figures, occupy space. They come in many shapes and sizes. Every prism has the following characteristics: Bases: A prism has two bases, which are congruent polygons lying in parallel planes. Lateral edges: The lines formed by connecting the corresponding vertices, which form a sequence of parallel segments. Lateral faces: The parallelograms formed by the lateral edges. A prism is named by the polygon that forms its base, as follows: Altitude: A segment perpendicular to the planes of the bases with an endpoint in each plane. Oblique prism: A prism whose lateral edges are not perpendicular to the base. Right prism: A prism whose lateral edges are perpendicular to the bases. In a right prism, a lateral edge is also an altitude.