What is the primary purpose of the USP?

The primary purpose of the United States Pharmacopeia (USP) is to protect the health of the public by ensuring the quality, safety, and efficacy of medicines, their ingredients, and related products. The USP establishes standards for the identity, strength, quality, and purity of drugs, which is essential for maintaining public health. By defining these standards and providing a comprehensive reference for healthcare providers and manufacturers, the USP plays a critical role in preventing potentially harmful variations in medicine quality that could adversely affect patient safety and effectiveness of treatment. This focus on safeguarding public health is why the answer is centered around this aspect of the USP's mission.