Tree Maps are those charts which are supposed to visualize the data which can be arranged hierarchically, where all elements have a parent (except for the root element). It looks like a rectangle divided into as many parts as there are categories (parent elements) in the Tree Map.
This Tree Map demonstrates the revenue got from exporting the 40 items of food. There are four food categories: fruits, vegetables, dairy and meat, each is a parent element for several food items. The root element (Products by Revenue) is placed in the top of the Tree Map table. Other parent elements are highlighted with the background of the cell colored in gray. Those cells with parent elements are clickable, so it is possible to click the parent item to see only the food items of this particular category. Hover an item to see how much money did this element bring to the company. There is a colorrange enabled in the chart, which can be used to highlight the elements of one of the revenue rate category.