Baud

Baud is the unit of symbol rate: one signal symbol transmitted per second. A symbol can represent one bit or multiple bits, so baud is not generally equal to bits per second.

Symbol rate: The number of signal symbols transmitted per unit time. Baud is the unit used to express symbol rate in symbols per second.
Digital signal: A signal whose information is represented by discrete values or states. Baud counts discrete signaling events in digital transmission.
Modem: A device that modulates and demodulates signals to transmit digital data over a communication medium. Modem specifications may state symbol rate separately from bit rate.
Bits per second: A unit measuring how many bits are transmitted or processed each second. It measures data rate, which can exceed baud when symbols encode multiple bits.
Symbol: A distinct signal state or waveform element chosen from a set to convey information. Each symbol counted by baud is one transmitted signal element, even if it encodes several bits.
Bit: A binary unit of information that takes one of two values. Bits are information units that symbols may encode in groups.
Serial communication: Data transmission in which bits are sent sequentially over a communication channel. Serial links use symbol timing to determine how quickly signaling proceeds.
Hartley (unit): A logarithmic unit of information equal to the information in one choice among ten equally likely alternatives. It measures information rather than the rate of transmitted signal symbols.
Modulation: The process of varying a carrier signal to encode information. Modulation maps symbols onto distinguishable changes in a transmitted waveform.
Constellation diagram: A plot showing the amplitude and phase states used by a digital modulation scheme. Its plotted points are the possible symbols whose transmission baud counts.

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Dial-up Internet accessRelated: Modem signaling rates are measured in baud, which differs from bits per second.