Which language did J.R.R. Tolkien create for the inscription on the One Ring?

J.R.R. Tolkien created the Black Speech of Mordor for the inscription on the One Ring.

The inscription begins, “Ash nazg durbatulûk,” translated as “One Ring to rule them all.” In Tolkien’s story, Sauron created the Black Speech for the servants of Mordor, and the Ring’s inscription uses its most famous verse. The writing appears in Tengwar letters, but the script and the language are not the same thing.

This distinction causes a common mix-up. Tengwar is a writing system used for several languages, while Black Speech is the language represented by the Ring inscription. Quenya and Sindarin are Elvish languages created by Tolkien, and Westron is the common language used by many peoples in the Third Age.