A sample space is the set of all possible outcomes of a random experiment. When you toss a coin, there are only two possible outcomes-heads (h) or tails (t) so the sample space for the coin toss experiment is {h, t}.
Any subset of possible outcomes for an experiment is known as an event. When an event is a single element of the sample space, it may be called a simple event. {h} and {t} are simple events for the coin toss experiment.
Example :
For the rolling of a single die, specify (1) the sample space of the experiment; (2) the event that a number less than 4 results and (3) the event that an even number results.
(1) {1, 2, 3, 4, 5, 6}
(2) {1, 2, 3}
(3) {2, 4, 6}