A proposition is a statement that expresses an idea or assertion that can be either true or false. In logic and philosophy, propositions are fundamental units of meaning that help in constructing arguments and reasoning. For example, the statement "The sky is blue" is a proposition because it can be verified as true or false. In mathematics, propositions are often used in proofs and theorems. They can be simple, like "2 + 2 = 4," or more complex, involving multiple variables and conditions. Understanding propositions is essential for fields such as logic, mathematics, and computer science, where clear and precise communication of ideas is crucial.