Final answer:
Commensalism, parasitism, and mutualism are three types of symbiotic relationships. Commensalism benefits one species without affecting the other, parasitism benefits the parasite while harming the host, and mutualism benefits both species involved.
Step-by-step explanation:
Commensalism is a symbiotic relationship in which an individual from one of the species benefits while the individual from the other species is unaffected. An example is a relationship between cattle egrets and grazing mammals, in which the egrets benefit and the mammals are unaffected. Parasitism is a symbiotic relationship in which an organism from one species, called the parasite, benefits, while the organism from the other species, called the host, is harmed. An example is a relationship between parasitic roundworms and human hosts.
Mutualism is a symbiotic relationship in which both species benefit. An example is a relationship between termites and protists where the protists digest cellulose for the termites, and the termites provide a protective environment and constant supply of food for the protists.