Geometric Dimensioning and Tolerancing (GD&T) is a system used in engineering and manufacturing to define the allowable variations in the size and shape of parts. It provides a clear and concise way to communicate the design intent, ensuring that parts fit together correctly and function as intended. GD&T uses symbols and annotations on technical drawings to specify geometric features, such as flatness, roundness, and parallelism. By using GD&T, engineers can improve the quality of their designs and reduce manufacturing costs. It helps in identifying critical dimensions and tolerances, allowing for better control during production. This system also facilitates clearer communication between designers, manufacturers, and quality control teams.