A biofilm is a collection of microorganisms, such as bacteria, that stick to surfaces and each other, forming a slimy layer. These microorganisms produce a protective matrix of substances, which helps them survive in various environments, including natural settings like rivers and man-made surfaces like pipes and medical devices. Biofilms can be beneficial or harmful. For example, they play a crucial role in natural ecosystems by aiding in nutrient cycling. However, they can also cause problems, such as infections in humans or clogging in water pipes. Understanding biofilms is important for improving health and industrial processes.