Quenya
Quenya was one of the languages spoken by the Elves. It was the tongue that developed among those non-Telerin Elves who reached Aman (the High Elves) from an earlier language called "Common Eldarin" (comp. Eldar).
Quenya had several branches -- Valinorean Quenya (spoken by the Noldor Elves in Aman), Vanyarin Quenya (spoken by the Vanyar Elves), and Exilic Quenya (spoken in Middle-earth after the Exile of the Noldor).
In the First Age, many of the Noldor committed terrible acts in their quest to retrieve the Silmarils, including the Kin-slaying of their fellow Elves. Due to this, the Sindarin king Thingol forbade Quenya to be spoken in his kingdom of Doriath. While the Noldor continued to speak Quenya among themselves, they used Sindarin to converse with other Elven clans. Over time, Quenya fell out of fashion as a spoken language in Middle-earth and was replaced by Sindarin as the common tongue of most Elves.
By the Third Age, Quenya was mostly regarded as an archaic language of lore and poetry. It was preserved by scholars and by the few Noldor Elves that remained in Middle-earth, such as Galadriel.