HISET Social Studies Practice 2025 - Free HISET Social Studies Practice Questions and Study Guide.

The purpose of the key, or legend, on a map is to explain the symbols and shading used throughout the map. It provides essential information that helps the map reader understand what different symbols represent, such as roads, rivers, mountains, or areas of different land use. For instance, without a key, a reader might not know what a specific color or symbol signifies, leading to confusion about the geographical information being presented.

In contrast, indicating population density involves specific data usually represented through charts or numerical values, which is not the primary function of a key. Showing physical geography pertains to the actual landforms and natural features depicted on the map rather than explaining the symbols themselves. While historical context can be important for understanding the significance of a location, it is separate from the operational purpose of the key in conveying map details. Hence, the key's role is pivotal for clarity and comprehension of the map's contents.