A legend is a key to the colors, symbols, and line styles that are used in a map. Legends are especially useful for maps of categorical data displayed in pseudo color, where each color represents a different feature or category. A legend can also be created for a single layer of continuous data, displayed in gray scale. Legends are likewise used to describe all unknown or unique symbols utilized. Symbols in legends should appear exactly the same size and color as they appear on the map (Robinson and Sale, 1969).
Use the Legend tool to automatically create color legends. Symbol legends are not created automatically, but can be created manually.