Polyurethane's chemical formula is written as C25H42N2O6. It is a polymer that forms foam.
Polyurethane is used in many common everyday items. Car seats are polyurethane cushions surrounded by a fabric or leather cover. Chair or seat cushion polyurethane foam is dense and sturdy, but it can be made to be as soft and supple as in a bed pillow. Carpet padding can be polyurethane as well, which is made into thin layers.
When making foam cushions, polyurethane starts out as a liquid that is easily poured into molds. The molds are fashioned into whatever custom shape is needed for a particular item.