The active site is a specific region on an enzyme where substrate molecules bind. This site has a unique shape and chemical environment that allows the enzyme to catalyze a chemical reaction efficiently. The interaction between the enzyme and substrate at the active site is crucial for the enzyme's function. When a substrate enters the active site, it forms an enzyme-substrate complex. This complex lowers the activation energy needed for the reaction, allowing it to proceed more quickly. After the reaction, the products are released, and the enzyme is free to catalyze another reaction, demonstrating its role in biological processes.