The active site is a specific region on an enzyme where substrate molecules bind and undergo a chemical reaction. This site is typically a small pocket or groove on the enzyme's surface, shaped to fit the substrate precisely. The interaction between the enzyme and substrate at the active site is crucial for catalyzing biochemical reactions efficiently. Enzymes, such as amylase or lipase, rely on their active sites to perform their functions. The unique structure of the active site allows for specificity, meaning that each enzyme can only catalyze certain reactions with particular substrates. This specificity is essential for maintaining proper metabolic processes in living organisms.