The three domains of life are bacteria, eukaryota and archaea. Each of these domains classifies a wide variety of life forms. For example, animals, plants, fungi and more all fall under eukaryota.
Until 1977, there were only two proposed domains of life: eubacteria and eukaryota. Carl Woese was the biologist who proposed the accepted three life form model. Each type of domain describes a different type of cell that organisms are made of. Eukaryotic cells have a nucleus that is bound by a membrane. Bacteria cells have no nuclear membrane and bacterial rRNA. Finally, prokaryotic (arhaea) cells have RNA markers and no nuclear membrane, but a different evolutionary history from bacteria.