What type of interaction is characterized by one organism benefiting while the other is harmed?

Parasitism is understood as a type of ecological interaction where one organism, known as the parasite, benefits at the expense of another organism, known as the host. In this relationship, the parasite derives nutrients or some form of advantage from the host, which often experiences detrimental effects as a result. This harm can manifest in various ways, such as reduced fitness, disease, or even death in extreme cases.

In contrast, mutualism describes interactions where both organisms benefit, while commensalism involves one organism benefiting without affecting the other. Symbiosis broadly encompasses a variety of long-term interactions between two species, including mutualism, commensalism, and parasitism, but does not imply harm to one of the parties involved in every instance. Therefore, parasitism is specifically defined by the asymmetrical nature of the benefit and harm, making it the precise answer to the question regarding interactions where one organism benefits while the other is harmed.