J.R.R. Tolkien’s academic specialty before he became famous for Middle-earth was philology.
Philology studies languages through their historical development, texts, and relationships. Tolkien specialized particularly in Germanic languages and medieval literature, drawing on Old English, Old Norse, Gothic, Welsh, Finnish, and other linguistic traditions.
His interest in language was not merely technical. He believed that languages could generate stories, cultures, and histories, and he often created a language before developing the people who spoke it. This approach helped produce the linguistic richness of Quenya, Sindarin, and other languages of Middle-earth.
Philology is sometimes confused with linguistics, literary criticism, or etymology. Those fields overlap, but Tolkien’s work combined close study of historical texts and language change with literary interpretation. His scholarship and fiction constantly influenced one another.