In nature, most bacteria do not exist as suspended (planktonic-free floating) cells. Bacteria live in a group (mass of bacterial cells) attached to each other and to surfaces, in a biofilm form.
A biofilm is as a complex community of microorganisms, embedded in self-created extracellular polymeric substances (EPS). Therefore, the biofilm is a microbial population adherent to each other and to surfaces or interfaces enclosed in the matrix. In this complex biofilm network of EPS, the bacterial cells perform less as individual cells and more as a collective living system, frequently creating channels to deliver nutrients and water to the cells located inside the biofilm.