In the binomial distribution, say, oh, what is the probability of getting a 5? And you just kind of look at that histogram or that bar chart, and you say, oh, that's the probability. But in a continuous probability distribution, or a continuous probability density function, you can't just say, what is the probability of me getting a 5? You have to say, what is the probability of me getting between, let's say, a 4.5 and a 5.5? You have to give it some range. And then your probability isn't given by just reading this graph. The probability is given by the area under that curve.