A USB-TTL serial USART module is a device that allows you to connect a microcontroller, like an Arduino, to a computer via a USB port. The module uses a USB-to-serial converter chip, like the PL2303 or YP-01, to translate the data sent over USB to a form that can be understood by the microcontroller's serial USART (Universal Synchronous/Asynchronous Receiver/Transmitter). This allows you to use the USB port on your computer to communicate with the microcontroller and send it commands, or to receive data from the microcontroller. The module also typically has a set of pins that you can use to connect it to the microcontroller, making it easy to interface the two devices.

This USB - TTL convertor will allow you to quickly add plug & play functionality to your project.

Please note that these USB -TTL convertors are officially obsolete. An improved USB-TTL convertor is available here: https://leobot.net/viewproduct.aspx?id=4209