Biofilms are communities of microbial cells and extracellular polymeric substances (EPS) attached to a surface. Bacteria exist preferentially in the biofilm state in nature and in many engineered systems. In this state, microbes tolerate antibiotics and disinfectants. Bacterial biofilms are now implicated in a wide range of human diseases and infections including cystic fibrosis, otitis media, chronic wounds, artificial joint and prosthesis infection, and many nosocomial infections. Biofilm-related infections and industrial fouling problems cost billions of dollars each year.