Epibiont, a term derived from the Greek words "epi" meaning on and "bios" meaning life, refers to an organism that lives on the surface of another organism, termed as the substrate. Synonymous terms for epibiont include epizoic, ectosymbiont, and phoresis. The concept of epibiosis encompasses a wide array of relationships, ranging from commensalism, where one organism benefits without harming the host, to parasitism, where the epibiont negatively affects the host's health. Epibionts can be found across various ecosystems, from marine environments, where barnacles attach to whales, to terrestrial habitats, such as birds hosting lice on their feathers. Regardless of the terminology used, epibionts play a significant role in the intricate web of interactions that make up the natural world.