In map borders, what component acts like a table of contents and introduction of a book?

The marginal information on a map serves as a critical component that functions like a table of contents and an introduction to a book. It provides essential details that help the reader understand the context and content of the map. This may include information such as the map's title, the area covered, symbols and colors used, and sometimes additional notes about the features represented on the map. By offering this foundational information upfront, marginal info helps orient the reader, similar to how an introductory section in a book lays out key themes and concepts.

In contrast, the legend primarily explains the symbols used on the map, the scale provides information about distance representations, and the grid helps with locating specific points on the map. While all these components contribute to the overall usefulness of a map, marginal information is particularly geared towards providing an overview that situates the reader in terms of what to expect, much like the beginning of a book.