Final answer:
Symbiosis refers to an interaction where two species coexist and at least one benefits. This includes mutualism (both benefit), commensalism (one benefits, one unaffected), and parasitism (one benefits, one harmed).
Step-by-step explanation:
The interaction where two species live together for a long time and at least one of them benefits is called symbiosis. In symbiotic relationships, at least one species benefits, and the other may also benefit, be unaffected, or be harmed. These interactions include mutualism, commensalism, and parasitism. Mutualism is a type of symbiotic relationship where both species benefit from the interaction. In commensalism, one species benefits while the other is neither helped nor harmed. Lastly, in parasitism, one species benefits at the expense of the other.