A biofilm is an aggregate of microorganisms that attach tenaciously to surfaces and to themselves. When the environment is favorable, the organisms remain attached and begin to exude a slimy, glue-like protective coating shielding the highly organized community from soaps, disinfectants, antibiotics, high-velocity water sprays and sterilization. Yet the battered surviving microorganisms are still capable of launching successful infections. This course will discuss the formation and function of biofilms in nature, in human infections generally, and on medical implants and instruments specifically. It will explain how the handling of instruments and addressing the hospital environment can influence biofilm formation, ultimately impacting patient recovery, survival, and quality of life.