J.R.R. Tolkien calls the script used for many Elvish languages Tengwar. In Tolkien’s invented history, the Tengwar are letters created by Fëanor in the First Age and later adapted for different languages and writing traditions.
The word tengwar is a Quenya plural meaning “letters.” The script is also called the Fëanorian characters, linking it to Fëanor, the Ñoldorin craftsman associated with the creation of the Silmarils.
Tengwar is a writing system, not a language. It can represent Quenya, Sindarin, and other languages, with spelling conventions changing according to the language being written. This is why the same script may appear in different modes.
Cirth is a separate runic writing system associated especially with the Dwarves, while Sarati is an earlier script attributed to Rúmil. Those names are common sources of confusion when discussing Tolkien’s invented scripts.