Modal logic is a type of formal logic that extends classical logic to include concepts of necessity and possibility. It uses modal operators, such as "necessarily" and "possibly," to express statements about what could be true or must be true in different scenarios. This allows for more nuanced reasoning about propositions beyond simple true or false values. In modal logic, statements can be evaluated in various contexts or "worlds," which represent different ways things could be. This framework is useful in various fields, including philosophy, computer science, and linguistics, as it helps analyze arguments involving uncertainty, obligation, and knowledge.