Enzymes are remarkable biological molecules that play a crucial role in catalyzing biochemical reactions within living organisms. They are proteins that act as biological catalysts, accelerating the rate of chemical reactions without being consumed in the process. This article explores the definition of enzymes, their nomenclature, the IUB classification system, factors influencing enzyme activity, enzyme action and inhibition, the concept of isoenzymes, and the significance of coenzymes in biochemical processes.