Biofilm is a group of microorganisms that are joined together on a surface. They adhere to each other with molecular strands called extracellular polymeric substances, or EPS.
Biofilms are diverse communities of bacteria and other microorganisms. They form primarily in moist environments or those that are conducive to bacterial growth, such as metals, plastics and medical equipment.
While a singe type of organism can create a biofilm, naturally occurring biofilms are commonly made up of many different types of bacteria, fungi, algae, yeasts and other micoorganisms.
Dental plaque and the build-up found in clogged drains are common examples of biofilm.