In a chart or graph in a spreadsheet program such as Microsoft Excel, the legend is often located on the right side of the chart or graph and is sometimes surrounded by a border. The legend is linked to the data that is displayed graphically in the plot area of the chart. Each specific entry in the legend contains a legend key for referencing the data.
Add a Legend to a Chart in Excel
To further the confusion between legends and keys, Microsoft refers to each individual element in a legend as a legend key. A legend key is a single-colored or patterned highlight in the legend. To the right of each legend key is a name that identifies the data represented by the specific key.
Depending on the type of chart, the legend keys represent different groups of data in the associated worksheet:
In Excel, legend keys are linked to the data in the plot area, so changing the color of a legend key also changes the color of the data in the plot area. You can right-click or tap and hold a legend key and choose Format Legend to change the color, pattern, or image used to display the data.