Source : Free On-Line Dictionary of Computing

modulo operator
     
         (mod) The operator that returns the remainder
        after integer division of its first argument by its second.
        Written as "%" in {C} and some other languages.
     
        Where the second argument is a power of two, the result can be
        calculated much more quickly using {bitwise and} with the
        appropriate {bit-mask}.
     
        (1999-07-12)