Protocols and standards
Baud
The baud measures how many signal state changes occur per second on a link — not to be confused with the bit rate, counted in bits per second.
Since one symbol can encode several bits, the two figures rarely coincide. The distinction matters for fax: the speeds negotiated between two machines denote a bit rate, but robustness depends on how many states the line can still tell apart. As it degrades, the machines lower the speed rather than give up.