The island rule helps explain why some mammals on archipelagos evolve into much smaller or much larger sizes than their mainland relatives.

To differentiate the product of two functions, use the product rule: (f·g)' = f'·g + f·g'.

Many philosophers argue that the silver rule—do not treat others in ways you would not want to be treated—offers a clearer ethical guide in difficult situations than more permissive norms.

The cafe's house rule is to remove your shoes before entering.

In our small company, the founder still rules the roost, making every major decision.

A private board can effectively rule the school, deciding budgets, hiring staff, and shaping the curriculum.

Before the tournament started, every player received a copy of the rule book.

The referee consulted the old rule-book before making his final decision.

The referee consulted the rule books before making the controversial call.

Before finalizing the tournament schedule, the committee consulted several rule-books to ensure compliance.