baud, baud rate A baud is the number of signaling elements per second sent by a communications device such as a modem, In theory, a modem with a high baud rate means fast transmission. The baud rate is therefore equal to the bit rate only if each signal element represents one bit of information.
Unfortunately, in much of today’s literature, the terms “baud” and “bits per second” are used synonymously. This is correct in cases where pure two-state signaling is used, but is incorrect in general. For this reason, the term “baud” is gradually being replaced by “bits per second,” since the latter is independent of the coding method and truly represents the information rate.
When you use a modem to send information from one computer to another over the phone lines, the information moves at a certain speed. This speed is measured in bits per second, a bit being one electronic unit of information. This bits-per-second rate is also commonly called the baud rate (pronounced “bod”). It’s a measure of how fast your modem can send and receive information. Modems most typically send at 1200, 2400, or 9600 baud.
Now, I do have to warn you that even though the masses (that’s us) often use the term “baud” to mean the same thing as “bits per second,” this is technically incorrect, and someday someone will surely scold you. One baud is actually one “modulation change” or one “signal event” per second on a communications channel. It’s only at 300 baud that one signal event equals one bit per second. A modem operating at 1200bits per second needs only one signal event to send 2 bits, so if you want to be persnickety you should call it a 600 baud modem. See bps for a discussion of common communications speeds and how they translate into speed ratings you can relate to.
The term “baud” is named after the inventor of the Baudot telegraph code, J.M.E. Baudot.