1. Mutualism: Both organisms benefit from the interaction.

* Example: Bees pollinate flowers, getting nectar as food, and the flowers are pollinated, allowing them to reproduce.

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

* Example: Barnacles living on a whale's skin. The barnacles get a place to live and food, while the whale is not affected.

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

* Example: A tapeworm living inside a human's intestines. The tapeworm gets nutrients from the human, while the human can experience health problems.

It's important to remember that these categories are not always clear-cut, and some relationships might fall somewhere in between.