Baud rate

In data communication, baud rate (sometimes called 'symbol rate) is the speed at which basic symbols are transferred across a communication link.

If the symbols used on the link have only two values (i.e. they are bits), then the baud rate and the bit rate are identical. However, some system use more complex signalling, and each symbol might have 4 potential values, in which case there would be 2 bits per symbol, and the bit rate would be twice the baud rate.

Most slower-speed serial lines, there is only one bit per symbol, but in higher-speed links, multi-bit symbols are common.