In telecommunication and electronics, baud (/bɔːd/; symbol: Bd) is a common measure of symbol rate, one of the components that determine the speed of communication over a data channel.
It is the unit for symbol rate or modulation rate in symbols per second or pulses per second. It is the number of distinct symbol changes (signaling events) made to the transmission medium per second in a digitally modulated signal or a bd rate line code.
Baud is related to, but not equivalent to, gross bit rate, which can be expressed as bits per second. If there are only two symbols in the system (typically 0 and 1), then baud and bits per second (bps) are equivalents.
The baud unit is named after Émile Baudot, the inventor of the Baudot code for telegraphy, and is represented in accordance with the rules for SI units. That is, the first letter of its symbol is uppercase (Bd), but when the unit is spelled out, it should be written in lowercase (baud) except when it begins a sentence. It was defined by the CCITT (now the ITU) in November 1926. The earlier standard had been the number of words per minute. One baud was equal to one pulse per second, a more robust measure as word length can vary.