There are two methods of data transmission used on OBD II systems. One method is the Universally Asynchronous Receiving/Transmitting (UART) protocol. UART is an interface device that allows a controller to send and receive serial data. Serial data refers to information that is transferred in a linear fashion (over a single line) one bit at a time. A data bus describes the electronic pathway through which serial data travels. UART receives serial data, converts the data to parallel format, and then places it on the data bus for use by the vehicle computer. UART can also convert data in parallel format to serial format, and then transmit the converted data to the Scan Tool.