Biofilms are viewed as one of the most common form in which microorganismsexist naturally in nature. In particular, bacterial biofilms play importantroles in industrial-based problems, disease and infection and have been studied ingreat detail. However, the intrinsic structure of a biofilm is not solidly understoodwhere postulations on mechanisms, structure, chemical and biological nature andthe community are still seldom reliably described. This chapter aims to highlightsome of the most important structures contained in a biofilm—in particular microstructures.It is the microstructure of a biofilm which governs its make-up, integrityand functionality, all of which will be discussed to some level of detail