A more thorough explanation:

Definition: Inclusio unius est exclusio alterius means that the inclusion of one thing implies the exclusion of another.

Example: If a sign says "No dogs allowed," it implies that other animals are allowed.

Explanation: This legal principle is often used in interpreting contracts and laws. It means that when a list of things is provided, anything not on the list is excluded. In the example, the sign specifically mentions dogs, which means that other animals are not prohibited.