What does a legend on a map do?

The legend on a map serves to explain what the symbols and markings mean, making it an essential component for understanding the information presented. Each symbol or color used on the map corresponds to specific features or data points, such as roads, parks, bodies of water, or elevation changes. By referring to the legend, a user can accurately interpret the map's visual language, ensuring they can navigate or analyze the area effectively. This understanding is crucial for tasks like planning a route or studying geographic features.

The other options provided connect with different aspects of map use but do not characterize the primary function of a legend. For example, while a scale indicates distance and is important for understanding measurements, it operates independently from the legend. Similarly, a legend does not describe the history of an area or display population density; those concepts pertain to other forms of map information.