Carolus Linneaus (1758) developed the system of binomial nomenclature in order to classify living things.  In this system, each living thing was given a generic name (genus) and specific epithet, both in Latin.  The two names are considered to represent a distinct species unlike any other form of life.

Living things are organized into more general groups, each of which shares some particular group of characteristics.
This can then be used to develop taxonomic schemes for the classification of organisms.

In 1970, Robert Whittaker developed a five-kingdom system of classification based on ecology, evolution and structure.

In 1980, Carl Woese proposed a new system based on ribosomal RNA (rRNA) analysis of many different types of cells.  Living things could be classified in three superkingdoms or Domains: Archea, Eubacteria and Eukarya based on each group's specific rRNA and other biochemical differences.