An agonist is a compound that binds to a receptor to produce the same response as an endogenous ligand. A full agonist is capable of producing the maximal response, greater than that of the endogenous ligand, while binding to a smaller number of receptors. This occurs due to the total conformational change of the receptor upon compound binding and allows for maximum activation of the receptor. Conversely, a partial agonist will produce less of a conformational change, which results in less activation and a lower efficacy. Even if a partial agonist were to bind to more receptors than needed to elicit a response, the efficacy and activation of the receptor would not change.