QuenyaQuenya is one of the languages spoken by the Elves in J. R. R. Tolkien's work. It was the language that developed among those Elves that reached Valinor (they are at times also called Eldar, "star-folk" or High Elves). The Three Houses of Elves (the Noldor, the Vanyar and the Teleri) spoke different, though mutually intelligible dialects of Quenya. The language was also adopted by the Valar who also made some new introductions into it from their own original language.
The Noldor that fled to Middle-earth following the Darkening of Valinor spoke Quenya among themselves. However when Thingol of Doriath, who was the king of the Sindar (silvan-Elves that stayed in Middle-earth all along) learnt about their slaying of the Teleri, he forbade the use of Quenya between his people and the Noldor, and forced them to communicate in Sindarin only.
The Quenya used in Middle-earth of the Third Age (the time of the setting of The Lord of the Rings) had come to be a scholarly-pursuit - something akin to Latin in our time. It was meant to be used as a formal language and for writing, and Sindarin was the vernacular of all Elves. However the Noldor still remembered it and valued it highly, which we can see in the way they treat Frodo's greeting elen síla lúumenn' omentielvo.
Its grammar is influenced by Finnish, being quite inflected. The phonology is also based on Finnish, and to a lesser extent Italian; namely, no consonant cluster can begin or end a syllable.
In our times, Quenya has a few publications of greater or lesser officiality, the more important being "Vinyar Tengwar" and "Parma Eldalamberon". A good course in Quenya grammar can be found at Ardalambion.
 With one exception, the dual dative ending -nt.