Archaebacteria, also known as Archaea, are a group of microorganisms that share characteristics with bacteria but are also distinct in their genetics and biochemistry. They are often found in extreme environments. Examples include: Methanogens, such as Methanobrevibacter smithii found in the human gut; Halophiles, like Halobacterium found in high-salt environments; and Thermophiles, like Sulfolobus found in hot springs. Elaboration:Methanogens:These Archaea produce methane as a byproduct of their metabolism. They thrive in anaerobic (oxygen-free) environments like swamps, marshes, and the guts of animals. Methanobrevibacter smithii is a well-known example found in the human digestive system. Halophiles:These organisms live in extremely salty environments, such as salt lakes and salt evaporation ponds. Halobacterium is a common example. Thermophiles:Thermophiles are adapted to high temperatures, often found in hot springs and hydrothermal vents. Sulfolobus is a well-studied example, thriving in acidic hot springs.