In geometry, a cylinder is a three-dimensional shape with a circular base, a circular top and straight sides. It is the solid figure that you get when you rotate a rectangle about one of its sides. In most cases when we talk about the volume of a cylinder, we are talking about how much liquid it can hold.
The strictly correct way of saying it is "the volume surrounded by a cylinder" - the amount of liquid it holds. But many textbooks simply tell "the volume of a cylinder" to mean the same thing.
