Multi-Series Bar Charts are usually used when there are several items distributed on any basis which values we need to compare.
In this multi-series bar chart the revenue from selling several products in several states are compared. Each series represents a state, so you can turn on/off or highlight (hover) a series by clicking or hovering its legend item. The products are the categories; all series are grouped in a way that makes the revenue difference clearly seen. As usual for Bar Charts, the horizontal axis is Y axis, it shows the revenue in dollars; the vertical axis is X axis with categories (product names). Each series has its own color. Tooltips are formatted to show the name of the product as a tooltip title and the state name and revenue from the given state are shown in tooltip body.