Population of various microorganisms, trapped in a layer of slime and excretion products, attached to a surface. Bacteria is one of the most common microorganisms and creates several colonies when it becomes fixed to a surface. As the colonies are bonded together through tiny projections on the surfaces, they become what is referred to as pilli. Pilli produces gum-like residue to the surfaces to keep all of the colonies stuck together, while releasing extremely rich nutrients to sustain the bacteria. In the off-chance that a bacteria cell does not possess the required enzyme that creates something like lactose in the environment, then pilli helps by changing the DNA of that cell to another. The newly acquired DNA will have the necessary genetic information to create the lactose, which ultimately makes the bacteria cell stronger. Biofilm development is aided through this whole process and many kinds of newer genetic material are adjoined, forming strong cells throughout the entire biofilm.