Active Pharmaceutical Ingredients (APIs) are the essential components in medications that produce the intended therapeutic effect. They are the biologically active parts of a drug that interact with the body to treat, prevent, or diagnose diseases. APIs can be derived from natural sources or synthesized through chemical processes. The quality and purity of APIs are crucial for ensuring the safety and efficacy of pharmaceutical products. Regulatory agencies, such as the U.S. Food and Drug Administration (FDA), set strict guidelines for the manufacturing and testing of APIs to ensure they meet necessary standards before being used in medications.