Source : Free On-Line Dictionary of Computing

bit rate
     
         (Or "bitrate") A
        {data rate} expressed in bits per second.  This is a similar
        to {baud} but the latter is more applicable to channels with
        more than two states.
     
        The common units of bit rate are {kilobits per second} (Kbps)
        and {megabits per second} (Mbps).  In data rates, the
        multipliers "k", "M", etc. stand for powers of 1000 not powers
        of 1024.
     
        The term is also commonly used when discussing digital
        {sampling} and {sample rates}.  For example, the {MP3} audio
        {compaction} algorithm is often set to ouput files with a
        bitrate of 120 kbps.  This means that the file contains an
        average of 120 kilobits for each second of audio (900 KB per
        minute).  This compares with {CD audio} which is encoded at
        44100 16-bit stereo samples per second or 1408 kbps.
     
        (2003-05-19)