Now, let's talk about purpose. What are the main purposes of visualization? Why do people use it or may want to use it? Okay, so there's one common characterization of information visualization purposes, and we have three main classes. The first one is explanatory visualization, then we have exploratory visualization, and confirmatory visualization. So let's see what these three categories mean. Explanatory visualization means that the main purpose of the visualization is to explain something to somebody else. So the idea is that their is someone who has some message or some idea that needs to be communicated visually through data visualization. And this person needs to design a visualization that is appropriate for explanation. The second one is exploratory. What does it mean? Well, it means that in this case, there is a person who needs to extract information out of data and doesn't really know what the content of this data is. So idea is that the main purpose of visualization, in this case, is to help the person answer questions and generate new hypotheses. The last one, which is somewhat similar, is confirmatory. What does it mean? Well, the difference, here, between confirmatory and exploratory is that the person who is using visualization here has some hypothesis or question in mind that needs to be checked out. So I all ready have a hypothesis, but I want to check whether my hypothesis actually holds in the data. And I use visualization, for instance, some charts, to verify whether my hypothesis is correct or not. One important thing to say is that the main purpose of explanatory visualization is to communicate something to somebody else. So there is always an audience of some sort. So this why we group this into a communication category. Whereas, exploratory and confirmatory analysis, most of the time, are about analyzing data. So there is a person who wants to reach some objectives by analyzing data. So, here, in order to make this concept a little bit more concrete, I want to give you a few examples. The first one is an example of an explanatory visualization.