A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, typically between 20 and 45 °C (68 and 113 °F). The term is mainly applied to microorganisms. Organisms that prefer extreme environments are known as extremophiles.
The habitats of these organisms include especially cheese, yogurt, and mesophile organisms are often included in the process of beer and wine making.
Organisms that prefer cold environments are termed psychrophilic, those preferring warmer temperatures are termed thermophilic or thermotrophs and those thriving in extremely hot environments are hyperthermophilic. Hyperthermophiles are a type of extremophile. All bacteria have their own optimum environmental surroundings and temperatures in which they thrive the most. A genome-wide computational approach has been designed by Zheng, et al. to classify bacteria into mesophilic and thermophilic. 
^Willey, Joanne M., Linda Sherwood, Christopher J. Woolverton, and Lansing M. Prescott. Prescott, Harley, and Klein's Microbiology. New York: McGraw-Hill Higher Education, 2008. Print.
^Hao Zheng and Hongwei Wu. Gene-centric association analysis for the correlation between the guanine-cytosine content levels and temperature range conditions of prokaryotic species. BMC Bioinformatics 2010, 11(Suppl 11):S7.