Nonwoven fabric is a fabric-like material made from staple fiber (short) and long fibers (continuous long), bonded together by chemical, mechanical, heat or solvent treatment. The term is used in the textile manufacturing industry to denote fabrics, such as felt, which are neither woven nor knitted. Some nonwoven materials lack sufficient strength unless densified or reinforced by a backing. In recent years, nonwovens have become an alternative to polyurethane foam.