The ability of microorganisms to survive under harsh conditions has recently prompted researchers to study these microbes to better understand their characteristics and eventually utilize them in various applications. Extremophilic microorganisms withstand one or more extreme condition constraints due to cold, heat, high acidity, high alkalinity, high salinity, and high pressure levels. These constraints would destroy normal microorganisms. Extremophiles can be classified according to the environment in which they survive. Many extremophilic microorganisms possess properties suitable for biotechnological and commercial uses. This article discusses the characteristics and future potentials of extremophiles.