A cylinder is a three-dimensional figure that has two circular bases that are parallel and equal in size, connected by a curved surface. The axis of a cylinder is the segment that connects the center of the bases. The height of a cylinder is the perpendicular distance between the bases. The radius of the cylinder is the radius of one of the bases. If the axis of a cylinder is not perpendicular to the bases, it is called an oblique cylinder. If the dimensions of a cylinder are known, then its volume and surface area can be calculated.