Symbiosis is a close and long-term interaction between two different species. It can be broken down into three categories:

* 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.

Since you're specifically asking about a relationship where at least one organism benefits, you're talking about either mutualism or commensalism.

Examples:

* Mutualism: Bees and flowers (bees get nectar, flowers get pollinated)

* Commensalism: Barnacles on a whale (barnacles get a place to live, whales are unaffected)

Let me know if you'd like more examples or want to delve deeper into any of these categories!