The Handset Diagnostic Interface (DFU) Windows Driver is a software driver that enables a Windows computer to communicate with mobile devices in DFU (Device Firmware Upgrade) mode. DFU mode is typically used in the context of firmware flashing or diagnostics, particularly on smartphones, tablets, or other handheld devices. It's commonly associated with devices like Apple iPhones and iPads when you need to update or restore the device's firmware using specialized software like iTunes or other device management tools.

When your device is in DFU mode, the Handset Diagnostic Interface driver helps establish a connection between the device and the computer, enabling tools to interact with the device at a low level (such as installing firmware, recovering the device, or performing diagnostics).