Until a few years ago the term "bacteria" was synonymous with the term "prokaryote". Then technology revealed the existence of numerous forms of prokaryotes that possess distinctive differences when compared to those prokaryotes we refer to as "bacteria". Therefore, we now have two domains of prokaryotes: the Archaea (Archaeprokaryota; Archaebacteria) and the Prokaryota (bacteria, Eubacteria, or Euprokaryota).
Prokaryotes are ubiquitous, and vary in terms of their nutritional modes, reproductive styles, habitats and so on. Some are photosynthetic, some are heterotrophic, some are decomposers and others are parasites. Some forms are unicellular, others are colonial.