The regulatory approval process depends on the type of FDA regulated product you intend to market. The U.S. FDA regulates drugs, biologics, medical devices, food, vitamin supplements, cosmetics, and veterinary medicines.
The U.S. FDA is comprised of 5 centers, the Center for Durgs and Radiological Health (CDRH) for medical devices, the Center for Drug Evaluation and Research (CDER) for drugs, the Center for Biological Evaluation and Research (CBER) for biologics, the Center for Food Safety and Applied Nutrition (CFSAN), and the Center for Veterinary Medicine (CVM).
Medical devices are divided into "Classes", Class I (the least regulated) and Class III (the most regulated). Drugs are Prescription (Rx) or Over-the-Counter (OTC) drugs. Some drugs are "controlled drugs" or "scheduled drugs", and these drugs have additional "Drug Enforcement Agency" requirements.
Class II-III medical devices require premarket approval (or clearance), as do Rx drugs and biologic products. Clinical trials are typically required for Rx drugs and biologic products, and Class III medical devices. Class II devices may required clinical studies.
All drug and device manufacturers must register with the FDA (the FDA issues an Establishment Registration Number), and each specific product must be listed with the FDA. Foreign firms importing products to the U.S. require an import agent in the U.S.