This volume serves as a comprehensive reference guide designed to catalog the geography, history, and inhabitants of J.R.R. Tolkien's fictional legendarium. David Day, an established scholar of Tolkien's work, synthesizes information from the primary texts to provide a structured index of Middle-earth and the Undying Lands. The book utilizes a combination of descriptive entries and visual aids to clarify the complex lore surrounding the author's world-building.

Readers frequently note the accessibility of the prose, which makes the dense mythology of Middle-earth easier to navigate for casual fans. Experts often highlight this as a foundational reference tool for those seeking to organize the vast array of names and places found within the legendarium.