Halophiles are classified into two categories: 1) extremely halophilic archaea, and 2) moderately halophilic bacteria. The extremely halophilic archaea have adapted to require high salt concentrations (2.5M) in the living environment by incorporating the high salt concentration into the cell. On the other hand, the moderately halophilic bacteria achieve living in a wide range of salt concentrations by synthesis or incorporation of organic compounds.