Porous metals are engineered materials; they are designed for special properties. Technological progress necessitates expanding the choices of such materials, making the development of new porous metals a relevant challenge for materials scientists.

Although a wealth of information has already been accumulated on these materials, new results are published every year, extending the engineer's capability to manufacture porous metals and revealing their unknown and often unusual properties. This survey describes the state of the art and some recent accomplishments in the field. This article discusses manufacturing practices, structure, properties, and applications of porous metals. Promising new research issues are also highlighted. Materials whose pores were not formed in situ, like honeycomb structures made by high-energy beams etc., are not covered.