A USB-to-Serial Adapter Windows driver is a software component that enables communication between a Windows computer and a device that uses a serial (RS232) interface, through a USB port. These adapters are commonly used when you need to connect older serial devices (like GPS units, industrial equipment, modems, or other legacy hardware) to a modern computer that does not have a built-in serial port.

A USB-to-Serial adapter typically contains a small chip that converts the USB protocol to a standard RS232 serial communication protocol. Examples of popular USB-to-Serial chipsets include the Prolific PL2303, FTDI FT232R, and Silicon Labs CP2102.