The book compiles the latest studies on microorganisms thriving in extreme conditions. Microbes have been found in extremely high and low temperatures, highly acidic to saline conditions, from deserts to the Dead sea, from hot-springs to underwater hydrothermal vents- the diversity is incredible. The various chapters highlight the microbial life and describe the mechanisms of tolerance to these harsh conditions, and show how an understanding of these phenomena can help us exploit the microbes in biotechnology. The theme of the book is highly significant since life in these environments can give vital clues about the origin and evolution of life on earth, as a lot of these conditions simulate the environment present billions of years ago. Additionally, the study of adaptation and survival of organisms in such environments can be important for finding life on other planets. This book shall be useful for students, researchers and course instructors interested in evolution, microbial adaptations and ecology in varied environments.