The fictional writing system Tolkien created for the Elves and used in Middle-earth is Tengwar.
Tengwar is a script whose name means letters or signs in Quenya. Tolkien designed it for use with several languages, including Quenya and Sindarin. Its letters are arranged according to phonetic features, so the shapes and related forms reflect how sounds are made rather than simply representing an alphabet copied from a real-world model.
The script appears in famous inscriptions and title pages connected with Middle-earth. The inscription on the One Ring is commonly written in Tengwar, although the language represented there is Black Speech rather than an Elvish language. This distinction is important: Tengwar is a writing system, not one single spoken language.
Cirth is another Tolkien-created script, especially associated with Dwarves and later adapted by other peoples. Sarati is an earlier script in Tolkien’s invented writing history, while Angerthas refers to a related runic system.