Purpose of Review: Bacterial biofilms have recently been shown to be important in diseases of the head and neck. Because the concept of biofilms is novel to most practitioners, it is important to gain a basic understanding of biofilms and to recognize that strategies developed to treat planktonic bacteria are ineffective against bacteria in a biofilm., Recent Findings: Bacteria preferentially exist in complex, surface-attached organizations known as biofilms. Bacteria in biofilms express a different set of genes than their planktonic counterparts and have markedly different phenotypes. Biofilm bacteria communicate with each other, and have mechanisms to diffuse nutrients and dispose of waste. Biofilms provide bacteria with distinct advantages, including antimicrobial resistance and protection from host defenses. Thus, bacteria exist in a far more complex fashion than previously thought and can best be thought of as "self-assembling multicellular communities." Although a focus on the planktonic form of bacteria has been useful in understanding acute infections, chronic infections are much better understood as biofilm illnesses. Biofilms have been shown to be involved in chronic otitis media, chronic tonsillitis, cholesteatoma, and device-associated infections., Summary: Now that basic research has demonstrated that the vast majority of bacteria exist in biofilms, the biofilm concept of disease is beginning to spread throughout the clinical world. Understanding that many of the infections that affect structures of the head and neck are actually biofilm related is fundamental to developing rational strategies for treatment and prevention.