In what type of relationship does one organism benefit while the other is harmed?

The relationship where one organism benefits while the other is harmed is known as parasitism. In this type of symbiotic interaction, the parasite derives nourishment and benefits from the host organism, which suffers negative effects as a result. Examples of parasitism include tapeworms living in the intestines of mammals or mosquitoes feeding on the blood of humans. The key characteristic that defines parasitism is the clear advantage that the parasite gains at the expense of the host's health and wellbeing. In contrast, mutualism involves both organisms benefiting, commensalism entails one benefiting while the other is not significantly helped or harmed, and competition occurs when two or more organisms vie for the same resources, which can be detrimental to both parties involved.