This article introduces the reader to the diversity and significance of extremophiles. Descriptions are provided of the habitat and ecology of thermophiles, psychrophiles (cold lovers), acidophiles, alkaliphiles, and halophiles. The industrial and commercial applications of extremophiles, such as the use of thermophilic microbial enzymes in PCR technology, are also described. Finally, the article discusses the evolutionary significance of extremophiles and their role in the restructuring the evolutionary tree of life.

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