The Gadget Serial driver in Windows is typically used for connecting devices that implement USB gadget functionality. USB gadgets are small devices or peripherals that can act as different USB devices (like serial devices, network adapters, etc.) depending on how they are configured. The Gadget Serial driver, specifically, allows the Windows system to recognize and communicate with a device that mimics a serial (COM) port over USB, often used for communication between microcontrollers, development boards, or other embedded systems.