The more blue the area, the fewer clicks there are in that area. The more red the area, the more clicks there are in that area. This heat map displays the concentration of clicks on the page. For example, below in Figure 3 is a heat map of a Webpage from the US Census Bureau Website. However, heat maps are a very flexible data visualization tool and can be used to represent data on other surfaces besides geographic maps. Shades of purple represent results closer to a 50-50 split between the two major political parties. The more red the county, the higher the percentage of Republican votes. The more blue the county, the higher the percentage of Democrat votes. This heat map presents county-level data of election results. Those who closely follow US elections are probably also familiar with heat maps such as the one below in Figure 2. In the map, temperature is represented by colors ranging from white, pink, red, orange, and yellow for the hotter temperatures (think “white-hot,” or “red-hot” for these hotter temperatures alternatively, think about the colors that make up a flame) to various shades of blue and (not depicted) purple (think “ice-cold”). Below in Figure 1 is an example of a temperature heat map of the United States-probably the most common and straightforward type of heat map-from November 3 rd, 2010. For example, when watching The Weather Channel, you’re very likely to see various geographic maps of the United States (or a particular region of the US) shaded with various colors representing one of many different types of meteorological data such as temperature and precipitation. Typically, heat maps take the form of an actual geographic map. Heat maps-graphical representations of data in which a spectrum of colors is used to represent the values of individual data points in a set of data-are very popular in the world of data visualization. If you’ve ever checked the weather or followed an election on television, you’re probably familiar with a specific form of data visualization known as a heat map.