**Cylinder**

A **cylinder** is a prism whose bases are curved surfaces rather than polygons.

A **circular cylinder** has bases which are circles, and a **right circular cylinder** is a right angled prism whose bases are circles. A typical soda can is a right circular cylinder. The line joining the centers of the bases is called the **axis** of the cylinder. Generally, when we say cylinder, a right circular cylinder is implied.

**Surface Area of a Cylinder**

To find the area of the curved surface of a cylinder, consider cutting the curved surface along the vertical line and ‘unrolling’ the surface.

We will form a rectangle, where one side of the rectangle is the altitude, of the cylinder, and the other is the circumference, , of the bases. To visualize this better, wrap a piece of paper around it. This should make it clear that the curved surface of a cylinder is actually a rectangle. Thus, the **Lateral Surface Area** of a cylinder is , and as the sum of the area of the curved surface and the two circular ends, we get

**Volume of a Cylinder**

Just as in the case of a cuboid, volume of a cylinder can be measured by filling it with circular sheets of paper.