The 4WD Hat module for the Raspberry Pi is an add-on board that allows a Raspberry Pi to control a 4-wheel-drive (4WD) robot. It includes motor drivers and connections for four DC motors, enabling the Raspberry Pi to control the movement of the robot in all directions. The module typically interfaces with the Raspberry Pi’s GPIO pins, allowing users to program and control the robot through various sensors and inputs. This module is commonly used in robotics projects, offering a simple way to add mobility to Raspberry Pi-based robots.