Instead of the number of alternatives N, scientists measure information in terms of a quantity called S, for “Shannon information.” S is defined as the logarithm in base 2 of N: S = log2 N. The advantage of using the logarithm is that the unit of measurement S = 1 corresponds to N = 2 (because 1 = log2 2), making the unit of information the minimum number of alternatives: the choice between two possibilities. This unit of measurement is called “bit.”
