Biological grouping is a term used to describe the classification of living organisms. SPECIES, GENUS, GENERA, and SET are all terms used to describe different levels of biological grouping. SPECIES is the most specific level of biological grouping, referring to a group of organisms that can interbreed and produce fertile offspring. GENUS is a more general level of biological grouping, referring to a group of closely related SPECIES. GENERA is an even more general level of biological grouping, referring to a group of closely related GENERA. Finally, SET is the most general level of biological grouping, referring to a group of organisms that share certain characteristics.