Maps are the primary tools by which spatial relationships are visualized. Maps, therefore, become important documents. There are several key elements that should be included each time a map is created in order to aid the viewer in understanding the communications of that map and to document the source of the geographic information used. The data frame is the portion of the map that displays the data layers. This section is the most important and central focus of the map document. In the example displayed at the end of this article, the data frame contains fire history for the community of Topanga. The legend serves as the decoder for the symbology in the data frame. Therefore, it is also commonly known as the key. Descriptions detailing any color schemata, symbology or categorization is explained here. In the legend below, the fire history schemata have been categorized with a graduating color scheme.
