What is the primary function of a map key or legend?

The primary function of a map key or legend is to explain the symbols and colors used on a map. This is crucial for understanding the information represented visually. Each symbol or color corresponds to specific features or data on the map, such as different types of roads, land use, bodies of water, or elevation levels. Without the key, readers might misinterpret the map's information or struggle to understand what the symbols represent.

While other elements like historical context, scale, and geographic features are also important in the context of maps, they serve different purposes. The historical context provides background, the scale indicates the relationship between distance on the map and actual distance, and geographic features refer to the actual elements depicted on the map itself. The legend’s primary role is focused on clarifying the visual language of the map.