A Karnaugh map (K-map) is a visual tool used in Boolean algebra to simplify logical expressions. It organizes truth values of variables in a grid format, allowing users to easily identify patterns and minimize complex logic functions. Each cell in the map represents a possible combination of input variables, making it easier to visualize relationships. Karnaugh maps are particularly useful in digital circuit design and computer science for reducing the number of gates needed in a circuit. By grouping adjacent cells that contain 1s, users can derive simpler expressions, leading to more efficient designs and implementations.