Here's a breakdown:

* Commensalism: A relationship where one organism benefits from the interaction, while the other is neither harmed nor helped.

Examples:

* Barnacles on whales: Barnacles attach themselves to whales and get a free ride, access to food, and protection from predators. The whale is unaffected.

* Remora fish and sharks: Remora fish attach themselves to sharks and get free transportation and food scraps. Sharks are unaffected.

* Birds nesting in trees: Birds find shelter and protection in trees, while the trees are unaffected.

It's important to note that in some cases, the relationship between organisms can be complex and difficult to categorize. A relationship that appears to be commensalism might actually have subtle benefits or harms for the "unaffected" organism that are not yet understood.