Biological subdivision is a way of categorizing living organisms based on their shared characteristics. The four terms used to describe this subdivision are SPECIES, GENUS, ORDER, and ecotype. SPECIES is the most specific level of classification, and it is used to describe a group of organisms that are very similar and can interbreed. GENUS is a higher level of classification, and it is used to group SPECIES that share more characteristics than those within the same SPECIES. ORDER is an even higher level of classification, and it is used to group genera that share more characteristics than those within the same GENUS. Finally, ecotype is the highest level of classification, and it is used to group orders that share more characteristics than those within the same ORDER.