Enzymes are remarkable biological catalysts that accelerate chemical reactions within living organisms, facilitating essential processes like digestion, metabolism, and DNA replication. These protein molecules possess specific three-dimensional shapes, enabling them to bind with particular substrates, forming enzyme-substrate complexes. Through this interaction, enzymes lower the activation energy required for reactions, thus speeding up their rate without being consumed in the process. Enzyme catalysis involves a series of steps: substrate binding, catalytic reaction, and product release. Factors such as temperature, pH, and substrate concentration influence enzyme activity. Enzymes exhibit remarkable specificity, with each enzyme catalyzing a particular reaction or a group of closely related reactions. Understanding enzyme kinetics and mechanisms is crucial in various fields, including medicine, biotechnology, and agriculture, where enzymes are harnessed for therapeutic purposes, industrial processes, and environmental remediation. This book presents the complex subject of enzymology in the most comprehensible and easy to understand language. Most of the topics introduced herein cover new techniques and the applications of enzymology. Through this book, we attempt to further enlighten the readers about the new concepts in this field.