What is the purpose of a legend in a chart?

The purpose of a legend in a chart is to define what certain colors or symbols represent. A legend is essential because it helps the reader understand the information presented visually within the chart. For instance, if different colors are used to represent various categories, such as sales data for different products, the legend will indicate which color corresponds to which product. This clear identification allows the viewer to interpret the data accurately and make informed conclusions based on the visual representation.

The other choices do not accurately describe the primary function of a legend. Summarizing the main points of the chart or providing data sources are tasks typically achieved through titles, footnotes, or accompanying text, rather than through a legend. Similarly, while a conclusion based on the data might be drawn from the chart as a whole, it is not the role of the legend to offer this conclusion; rather, it serves as a guide to understanding the visual elements of the chart itself.