Enzymes are proteins that catalyze (speed up) chemical reactions within living organisms. They are highly specialized and can only catalyze specific reactions. Enzymes are essential for many biological processes, including digestion, metabolism, and DNA replication. They also have many industrial and commercial uses, including in food processing, pharmaceuticals, and laundry detergents. Understanding the structure and function of enzymes is an active area of research in biochemistry and molecular biology.