Division Archaebacteria, also known as Archaea, is a group of unicellular microorganisms that live in extreme environments such as hot springs, salt flats, and deep-sea hydrothermal vents. Synonyms for this division include Archaeons, archaebacteria, and ancient bacteria. Archaeons are the oldest living organisms on Earth and play a critical role in various biological processes, from nitrogen fixation to the breakdown of organic matter. Exploring synonyms for this division enables a better understanding of the diverse nature and importance of these microorganisms in various fields ranging from biotechnology to environmental science.