The Archaea, or archaebacteria, are the prokaryotic group most closely related to eukaryotes. This is due to the similarity of genes and metabolic processes that both Archaea and eukaryotes posses. One major similarity are the enzymes involved in transcription and translation.
Archaea or archaebacteria are unicellular microorganisms that are distinct from eubacteria and, although they possess some similar characteristics, are also distinct from eukaryotes. They are similar to eubacteria in that they lack a cell nucleus. They are known for their ability to exist in extreme environmental conditions such as high heat and salty environments. Examples of these organisms include the halophiles, methanogens and thermophiles.