a group of living organisms consisting of similar individuals capable of exchanging genes or interbreeding. The species is the principal natural taxonomic unit, ranking below a genus and denoted by a Latin binomial, e.g. Homo sapiens.
Carl Linnaeus classified all living things into groups based upon their physical features. His system placed organisms with the most similar characteristics together in a group he called the “species”. A species is defined as all organisms that are able to breed with one another, and most importantly, are able to produce fertile offspring. The species group is accepted as the smallest unit of biological classification and is always given a Greek or Latin name. The emergence of a new species from an existing one happens as a result of natural selection. This process is called speciation. Some scientists believe that speciation occurs continuously over long periods of time, whilst others believe that speciation occurs only rarely, and in relatively short bursts, sometimes as a result of a dramatic environmental event.