Classification Classification in biology, is the identification, naming, and grouping of organisms into a formal system. The vast numbers of living forms are named and arranged in an orderly manner so that biologists all over the world can be sure they know the exact organism that is being examined and discussed. Groups of organisms must be defined by the selection of important characteristics, or shared traits, that make the members of each group similar to one another and unlike members of other groups. Modern classification schemes also attempt to place groups into categories that will reflect an understanding of the evolutionary processes