Velvet is a type of fabric that is smooth on one side and tufted on the other side. The tufts are fine and even and give velvet a very soft, rich feel. Velvet has a pile and the sheen will change if you stroke it in different directions.
Velvet can be made from anything - velvet is simply the name for the weave. The best velvet is made from silk, but it can also be made from cotton or artificial fibres like nylon or polyester.