Polystyrene was first manufactured by BASF in the 1930s, and is used in numerous plastic products. Its most common use, however, is as expanded polystyrene, which is a mixture of about 5% polystyrene and 95% air. This is the material of which coffee cups and takeaway food containers are made.
In the USA it is made by the Dow Chemical Company under the tradename styrofoam. The word styrofoam is often used by the general public to indicate any brand of polystyrene foam.