Now when you're dealing with discrete data, that little nuance about having infinite numbers of possible values goes away, and we call that something different. So that is a probability mass function. If you're dealing with discrete data, you can talk about probability mass functions. Here's a graph to help visualize this:

For example, you can plot a normal probability density function of continuous data on the black curve shown in the graph, but if we were to quantize that into a discrete dataset like we would do with a histogram, we can say the number 3 occurs some set number of times, and you can actually say the number 3 has a little over 30% chance of occurring. So a probability mass function is the way that we visualize the probability of discrete data occurring, and it looks a lot like a histogram because it basically is a histogram.