Prism

A prism is a polyhedron meaning that all the sides must be straight lines
A prism has the same cross section across its whole length
A cylinder is therefore not a prism

Triangular Prism

Square Prism

A square prism is called a Cube and is an example of a regular polyhedron

Rectangular Prism

A rectangular prism is called a Cuboid
8 corners and 12 edges
6 faces that are all rectangles

Pentagonal Prism

Hexagonal Prism

Octagonal Prism