The extreme microbiomes are those microorganisms thriving under extreme conditions where no other living being will have any chance to survive. The extreme habitats are those presenting high temperatures (thermophiles), low temperature (psychrophiles), hypersaline environments (halophiles), low and high pH (Acidophiles/alkaliphiles), high pressure (Piezophiles) are distributed worldwide. The extreme habitats have proved to offer a unique reservoir of genetic diversity and biological source of extremophiles. The extremophilic microbial diversity and their biotechnological potential use in agricultural and industrial applications will be a milestone for future needs. Extremophiles and their cell components, therefore, are expected to play an important role in the chemical, food, pharmaceutical, paper and textile industries as well as environmental biotechnology.