S lists all the possible outcomes of a random phenomenon.
This definition of probability requires N to be finite. For example, a single card is picked from an ordinary 52 card deck. The other approach to probability is if we think of probability as a longrun relative frequency. The relative frequency approach to probability states that if an experiment is conducted a large number of times, the probability of that event will become stable and equal to the relative frequency. The sample space, S, contains all possible outcomes of an experiment, therefore always has a relative frequency of 1.