An extreme environment exhibits extreme conditions which are challenging to most life forms. These may be extremely high or low ranges of temperature, radiation, pressure, acidity, alkalinity, air, water, salt, sugar, carbon dioxide, sulphur, petroleum and many others.
An extreme environment is one where humans generally do not live. There are organisms referred to as extremophiles, that inhabit these spaces and are so well-adapted that they readily grow and multiply.
Examples of extreme environments include the geographical poles, very dry deserts, volcanoes, deep ocean trenches, upper atmosphere, outer space and other planets.