Enzymes are proteins that catalyze chemical reactions in the body. They are essential for many functions such as digestion, metabolism, cell growth and cell division. Enzymes work by binding to specific substrates, changing their shape, and allowing chemical reactions to occur more easily. There are thousands of different enzymes in the body, each with a specific function and structure. Enzymes can be classified into several groups, such as hydrolases, oxidoreductases, transferases, and lyases, based on the types of reactions they catalyze.