Use it as a reference when characters travel. When Tolkien says the Fellowship traveled 20 miles in a day, you can see exactly where that put them on Fonstad’s terrain maps.
It includes tactical layouts for major conflicts like the Battle of Pelennor Fields and Helm’s Deep. The Atlas of Middle-Earth
Tolkien didn't map everything. Fonstad clearly notes in the text where she had to use "geographic logic" to fill in gaps that Tolkien left vague. 5. Why It’s Unique Use it as a reference when characters travel
Fonstad uses colored or dashed lines to track the movements of the Fellowship, Bilbo’s company, and even Beren and Lúthien. and even Beren and Lúthien.