So if you're talking about a coin flip, well then the sample space is going to be the set of all the possible outcomes. So you could get a heads, or you could get a tails. That right over here is the sample space for the coin flip. So, and it's very useful because, for example, if these are equally likely outcomes, and you say, well what's the probability of the event of a heads? You say, okay, that's one out of the two equally likely outcomes. Or you can even construct, once you know all the possible outcomes, even if they aren't equally likely, you could say, well let's create a probability distribution. We at least know what the sample space is.