So this is my coin here. Doesn't even have to be a fair coin. Let me just draw this really fast. So that's my coin. And let's say on a given flip of that coin, the probability that I get heads is 0.6, and the probability that I get tails, well, it would be one minus 0.6, or 0.4. And what I'm going to do is I'm going to define a random variable X as being equal to the number of heads after 10 flips of my coin. Now what makes this a binomial variable?