A biofilm is a structured community of microorganisms—such as bacteria or fungi—that attach to a surface and produce a protective, glue-like matrix around themselves. This matrix, often made of sugars, proteins, and DNA, allows the microbes to adhere firmly to surfaces like teeth, medical devices, pipes, or tissues in the human body. Within a biofilm, microorganisms can communicate and cooperate, creating a highly organized environment that enhances their survival compared to free-floating (planktonic) cells.

Biofilms are important in human health because they can make infections more persistent and difficult to treat. The protective matrix can reduce the effectiveness of antibiotics and shield microbes from the immune system. Common examples include dental plaque on teeth and biofilms associated with chronic wounds or implanted medical devices. While many biofilms are harmless or even beneficial in natural environments, those that form in the body or on medical equipment can contribute to ongoing inflammation and infection, requiring targeted strategies for prevention and management.