The faces of a triangular prism are parallelograms while the two bases are triangles. This gives the prism three faces. In a regular prism, the faces are rectangles. However, some prisms lean to one side and are oblique.
By definition, the bases of a prism are parallel, and the faces are flat. Any cross-section of a prism parallel to the base results in an identical triangle to the base. Objects with curved sides, including cylinders, are not prisms even though their bases are parallel. The volume of the prism is the area of the base multiplied by the height. Glass or acrylic prisms reflect and refract sunlight, separating it into the seven colors of the rainbow.