Despite popular belief, most microorganisms do not live as free-swimming or -floating invaders in a liquid sea or move through our blood or lymphatic system. Neither do they exist as discrete colonies growing tidily on agar plates in a laboratory. Bacteria in typical lab cultures act nothing like the ones encountered in nature. Rather they occur as mixed populations inside what are termed "biofilms."¹ Up to 99% of bacteria live this way. The ability to form biofilms is one of the most remarkable characteristics of bacteria. This mode of bacterial growth has attracted particular attention because many persistent and chronic infections, including periodontitis, otitis media, biliary tract infections, lung and prostate infections, kidney stones and endocardititis, as well as the colonization of medical implants, are believed to be intrinsically linked to the formation of bacterial biofilms.²