Propositional logic is a branch of logic that deals with propositions, which are statements that can be either true or false. It uses logical connectives like "and," "or," "not," and "if...then" to form complex statements from simpler ones. Each proposition is represented by a variable, making it easier to analyze logical relationships. In propositional logic, the truth values of these propositions can be combined to evaluate the overall truth of compound statements. This system is foundational in fields like mathematics, computer science, and philosophy, as it provides a formal framework for reasoning and argumentation.