Enzymes are proteins that act as biological catalysts, which accelerate the rate of biochemical reactions taking place inside a living organism. Biological processes such as respiration, digestion, excretion, and metabolic processes that take place within the cells are performed with the help of enzymes necessary for sustaining life. Enzymes are affected by various environmental factors such as pH level and temperature. There are six types of enzymes, namely, oxidoreductases, hydrolases, lyases, transferases, isomeras, and ligases. Enzymes are used in various fields. They are specifically used in the field of biotechnology. Enzymes are used as industrial catalysts, therapeutic agents, manipulative tools, and analytic reagents. In medicine, they are used in making cultures and developing medicines. This book provides significant information on enzymes and their biotechnological applications. A number of latest researches have been included to keep the readers updated with the global concepts in this area of study. Researchers and students in the field of biotechnology will be assisted by this book.