A bubble chart is a two-dimensional graph that visualizes three data points simultaneously. The x and y axis depict two of the data points, while the size of the bubbles represent the third. Bubble charts are used to compare and contrast different elements within a dataset, making them an important tool for understanding the relationships between different variables. They are particularly well-suited for displaying multiple series of related data, such as population trends or economic performance. By using color, shape, and size to its advantage, a bubble chart can be an effective way to easily highlight key patterns in a set of data.