Active pharmaceutical ingredients (APIs) are the substances in medications that produce the intended therapeutic effect. They are the key components that make a drug effective in treating specific health conditions. APIs can be derived from natural sources or synthesized in laboratories, and they are essential for the formulation of various types of medications, including tablets, capsules, and injections. The quality and purity of APIs are crucial for ensuring the safety and efficacy of pharmaceuticals. 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.