A cylinder is a three-dimensional geometric shape with two parallel circular bases connected by a curved surface. The distance between the bases is called the height, while the radius is the distance from the center of the base to its edge. Common examples of cylinders include objects like cans, tubes, and pipes. In mathematics, the volume of a cylinder can be calculated using the formula V = \pi r^2 h , where r is the radius of the base and h is the height. The surface area can be found using the formula A = 2\pi r(h + r) . Cylinders are widely used in engineering and design due to their strength and efficiency.