When it comes to charts, what usually springs to mind are bar graphs, pie charts, trend lines, and so on. These are categorized based on graphical dimensions, which often leads to the misuse of charts.

The purpose of a chart is to help us better understand data. The key question to answer when choosing a chart is "What data do I have, and what do I need the chart to do?", not "What does the chart look like?". Therefore, we start from the data and classify charts based on their functions.