Source : Free On-Line Dictionary of Computing

bitwise
     
         A bitwise operator treats its operands as a
        {vector} of {bit}s rather than a single number.  {Boolean}
        bitwise operators combine bit N of each operand using a
        {Boolean} function ({NOT}, {AND}, {OR}, {XOR}) to produce bit
        N of the result.
     
        For example, a bitwise AND operator ("&" in {C}) would
        evaluate 13 & 9 as (binary) 1101 & 1001 = 1001 = 9, whereas,
        the logical AND, ({C} "&&") would evaluate 13 && 9 as TRUE &&
        TRUE = TRUE = 1.
     
        In some languages, e.g. {Acorn}'s {BASIC V}, the same operators
        are used for both bitwise and logical operations.  This
        usually works except when applying NOT to a value x which is
        neither 0 (false) nor -1 (true), in which case both x and (NOT
        x) will be non-zero and thus treated as TRUE.
     
        Other operations at the bit level, which are not normally
        described as "bitwise" include shift and rotate.
     
        (1995-05-12)