Some of the archaebacteria cannot undergo a moderately unsalty environment such as seawater. Life on Earth can be divided into three large collections or domains. These archaebacteria can live in absence of oxygen.
The Domain Archaea wasn't acknowledged as a main domain of life till quite freshly. Until the 20th century, most biologists acknowledged all living things to be classifiable as either a plant or an animal. But in the 1950s and 1960s, most biologists realized that this system missed accommodating the fungi, protists, and bacteria.
By the 1970s, a system of Five Kingdoms had arrived to be admitted as the model by which all living things could be arranged. At a more primary level, a definition was made within the prokaryotic bacteria and the four eukaryotic kingdoms (plants, animals, fungi, & protists).
Some of the examples of archaea: Euryarchaeota, Crenarchaeota, Bathyarchaeota.