The logical operator which reverses the value of the logical expression it operates on. Parentheses are strongly recommended as Not can affect variables directly. Not 0 would evaluate as a logical value ( being zero would be False and not being zero would be evaluated as True). Say a = 0. Thus, 0 is False, Not would then be Not False, which is True. True has the numeric value -1, so the expression would become -1 0, which is False. However,using parentheses, we have Not (a 0) yields Not (0 0) which yeilds Not( False), which yeilds True.Logical operator precedence: Not, And, Or.