Ectoparasites are a group of organisms that live on the external surface of a host organism. They include a variety of arthropods, such as fleas, ticks, lice, and mites. While the term ectoparasites is widely used, there are several synonyms that are commonly used to describe these organisms. One such term is external parasites, which refers to any organism that lives on the surface of a host. Other synonyms include exoparasites, ectozoa, and epizoa. No matter what term is used, ectoparasites can cause a variety of problems for their hosts, including irritation, disease transmission, and blood loss. Therefore, controlling these parasites is an important part of any animal health management program.