The relationship between two organisms in which one organism is benefited and the other one is harmed is called parasitism.
Parasites are organisms that live in or on the body of another organism from which it obtains food and cause harm to the host.eg. Mosquitoes, round worm, tape worm,
Host:- the organism in which the parasite lives in and obtain its food.
Ectoparasite – The parasite which lives outside body of the host. E.g. Mosquitoes.
Endoparasite – The parasite which lives inside the body of the host.
Vector – Many endo parasites do not have locomot0ry organs to move from one host to another. They employ some medium to carry them from one host to another. These mediums are called vectors.