A monoclonal antibody is a laboratory-made molecule designed to target specific proteins in the body. These antibodies are created from a single clone of immune cells, which means they are identical and can bind to the same part of a target protein. This specificity makes them useful in diagnosing and treating various diseases, including some types of cancer and autoimmune disorders. Monoclonal antibodies work by either marking harmful cells for destruction by the immune system or blocking the action of specific proteins that contribute to disease. They are a key component of targeted therapies and have been instrumental in the development of treatments for conditions like COVID-19 and certain cancers.