The science of naming, describing and classifying organisms is called "taxonomy." Through 250 years of research, scientists have named approximately 1.78 million species, as of 2014, of the estimated 5 to 30 million species on Earth.
A species is defined as any organism that breed or produce offspring with other similar subspecies. Zebras and horses are related, for example, but they cannot interbreed and thus are considered different species. When a new species is identified, it is named in Latin with a binomial name, consisting of the genus and species names. Genetic studies have augmented older techniques to classify animal and plant species.