This document provides information on therapeutic antibody drugs that have been approved by the FDA. Over 60 antibody drugs have been approved for treating various diseases like cancer, immune disorders, and infections. In 2016, worldwide revenues from antibody drugs reached almost $89 billion. There are currently 550 antibodies in clinical development. Soon after monoclonal antibodies were first described in 1975, they became valuable research tools for diagnosis and investigation. New technologies now allow for fully human antibodies to be isolated. The development of therapeutic antibodies is described in detail to help scientists understand this area of research.