A sequence of 0's and 1's, or any sequence of any "alphabet" of symbols, need not represent a number. It may just be a code that needs to be translated into some action.
Still, it is useful to know how many actions are possible. Our way of getting a handle on the situation is to talk about how many bits of information there are in a sequence of given length composed of symbols drawn from a chosen "alphabet" (for example, {A, G, T, C}).


As we have seen, the number of bits of information in a sequence of length 12 with symbol alphabet {0, 1} is exactly 12, IF neither of the two symbols is favored (they each have a 50/50 chance of occuring (p=0.5 for both)). On the next page we'll change our alphabet to the RNA alphabet, {A,G,U,C}.
