Aron*
Bacterial biofilms are formed by communities that are embedded in a self-produced matrix of extracellular polymeric substances (EPS). Importantly, bacteria in biofilms exhibit a set of 'emergent properties' that differ substantially from free-living bacterial cells. Bacterial biofilms can be considered to be an emergent form of bacterial life, in which communal life is completely different from bacteria that live as free-living cells. Emergent properties of bacterial biofilms include social cooperation, resource capture and enhanced survival following exposure to antimicrobials, and cannot be understood and predicted through the study of free-living bacterial cells. The physical scaffold of biofilm life is the matrix of extracellular polymeric substances (EPS) that keeps cells in the biofilm together and attaches them to substrata when colonizing surfaces. The matrix underlies the emergent properties of biofilms. The emergent properties of the biofilm are the reason for the evolutionary success of biofilms and underlie the role of biofilms as global habitat formers.