Symbiosis is a close and often long-term interaction between two different biological organisms. There are different types of symbiotic relationships, including:

* Mutualism: Both organisms benefit from the relationship.

* Commensalism: One organism benefits, while the other is neither harmed nor helped.

* Parasitism: One organism benefits at the expense of the other.

In each of these cases, one organism relies on the other for something essential to its survival, whether it be food, shelter, protection, or something else.