This is a USB 2.0 to TTL UART Converter Module.  This module is used when you want to quickly and easily convert RS232 serial interface component to USB.  The CP2102 IC that operates at the heart of this device is an all-in-one USB-to-UART Bridge Controller.  It allows for simple updating and integrating of RS-232 designs to USB while using a minimum of components and no external devices.  If you are looking to quickly and easily add a USB interface to your embedded project this is the device you need!