A measurement of digital signalling speed, often (and wrongly) used interchangeably with bits per second (bit/s) to specify the data-throughput rate of a modem. Strictly speaking, the two are equivalent only when one discrete signalling condition (baud) is used to represent one bit of data: this is true at low speeds only (under 300 bit/s); at higher speeds, several bits of data are encoded in a single baud. The distinction will be visible to most people as a difference in the computer's setting for 'baud rate' and 'bit rate.'
From: Communications

A unit of measurement that denotes the number of bits that can be transmitted per second. For example, if a modem is rated at 9600 baud it is capable of transmitting data at a rate of 9600 bits per second. The term was derived from the name of J.M.E. Baudot, a French pioneer in the field of printing telegraphy.
From: Information Technology

A measurement of digital signalling speed, often (and wrongly) used interchangeably with bits per second (bit/s) to specify the data-throughput rate of a modem. Strictly speaking, the two are equivalent only when one discrete signalling condition (baud) is used to represent one bit of data: this is true at low speeds only (under 300 bit/s); at higher speeds, several bits of data are encoded in a single baud. The distinction will be visible to most people as a difference in the computer's setting for 'baud rate' and 'bit rate.'
From: Internet