Biofilmandbiofoulingrefer to biological deposits on any surface. Biofilms consist of both microbes and their extracellular products, usually polysaccharides. The purpose of biofilm is to protect the microbes from hostile environments or to act as a trap for nutrient acquisition. Biofilm formation causes problems in many branches of industry, such as in industrial water systems and the medical and process industries. Besides causing problems in cleaning and hygiene, biofilm may cause energy losses and blockages in condenser tubes, cooling fill materials, water and wastewater circuits, and heat exchange tubes, and on ship hulls. Biofilm can also present microbial risks due to the release of pathogens from cooling towers or by reducing water quality in drinking water distribution systems. In the medical industry biofilm is referred to asglycocalyxwhen diseases of the lungs or the gastrointestinal or urinary tract are involved.