Counterexample

A counterexample is an example used to show that a particular statement or rule is false. When someone claims something is always true, a counterexample provides an instance where the statement doesn't hold, proving it incorrect. For example, if someone states "All birds can fly," a counterexample would be a penguin, which is a bird that cannot fly. Counterexamples are essential in logic and mathematics because they help test the validity of claims and clarify the limits of general statements. They demonstrate that a statement is not universally true by offering specific, real-world exceptions.