In the Third Age, the time of the setting of The Lord of the Rings, Quenya was learnt as a second language by all Elves of Noldorin origin, and it continued to be used in spoken and written form, but their mother-tongue was the Sindarin of the Grey-elves.

[T 4][4] The Lord of the Rings, according to Tolkien, "was primarily linguistic in inspiration and was begun in order to provide the necessary background of 'history' for Elvish tongues".

He usually started with the phonological system of the proto-language and then proceeded by inventing for each daughter language the necessary sequence of sound changes.

While its development was a continuous process, Quenya underwent a number of major revisions in its grammar, mostly in conjugation and the pronominal system.

[T 7] Another characteristic of Quenya reminiscent of ancient natural languages like Old Greek, Old English or Sanskrit is the dual grammatical number which is used in addition to singular and plural.

[12] Some linguists have argued that Quenya can be understood as an example of a particular kind of artificial language that helps to create a fictional world.

[19] Attempts by fans to write in Quenya began in the 1970s, when the total corpus of published Elvish comprised only a few hundred words.

[23] The Tolkien scholar Verlyn Flieger observed that the "degree of proximity" to the light of the Valar affected the development of both languages in terms of phonology, morphology and semantics.

Among the Eldar, i.e. those Elves who undertook the Great March to Valinor and Eldamar, Primitive Quendian developed into Common Eldarin.

The Elves derived some loanwords from the Valar's language, which was called Valarin in Quenya, although these were more numerous in the Vanyarin dialect than in Noldorin.

Tolkien explained that "the word Quenya itself has been cited as an exempla (e.g. by Ælfwine), but this is a mistake due to supposition that kwenya was properly kwendya and directly derived from the name Quendi 'Elves'.

"[T 19] The Elves of the Third Clan, or Teleri, who reached Eldamar later than the Noldor and the Vanyar, spoke a different but closely related tongue, usually called Telerin.

But Elu Thingol, King of the Sindar of Beleriand, forbade the use of Quenya in his realm when he learned of the slaying of Telerin Elves by the Noldor.

[T 20] By doing so, he both restricted the possibility of the Sindar to enhance and brighten their language with influences from Quenya and accelerated the "dimininution and spiritual impoverishment" of the Noldorin culture.

[T 21] From the Second Age on, Quenya was used ceremonially by the Men of Númenor and their descendants in Gondor and Arnor for the official names of kings and queens; this practice was resumed by Aragorn when he took the crown as Elessar Telcontar.

Typical Finnish elements like the front vowels ö, ä and y are lacking in Quenya, but phonological similarities include the absence of aspirated unvoiced stops or the development of the syllables ti > si in both languages.

[8] The combination of a Latin basis with Finnish phonological rules resulted in a product that resembles Italian in many respects, which was Tolkien's favourite modern Romance language.

(This may not be true in Vanyarin Quenya, given the word Aldudénië, the name of a lament for the death of the Two Trees of Valinor composed by Elemmírë of the Vanyar.

[T 23] The pronunciation of the consonant cluster ⟨hy⟩ is [ç] in Noldorin Quenya, which is a "strong voiceless y, similar to, but more frictional than the initial sound in English huge".

The primitive consonant clusters sm- and sn- came out in Quenya as ⟨m⟩ and ⟨n⟩; it has been suggested that there was an intermediate stage of ⟨hm⟩ and ⟨hn⟩, the voiceless versions [m̥] and [n̥], in Common Eldarin; these soon merged with the voiced ⟨m⟩ and ⟨n⟩.

[31] This interpretation is based on a statement by Tolkien, saying that ⟨é⟩ and ⟨ó⟩, when correctly pronounced by Elves, were just a little "tenser and 'closer'" than their short counterparts: "neither very tense and close, nor very slack and open".

As with all parts of Quenya grammar, the pronominal system was subject to many revisions throughout Tolkien's life, and the available corpus was not systematic until a list of endings was published in Vinyar Tengwar No.

[42] Such emphatic disjunctive pronouns, were already present in early Quenya but differed from the later versions (e.g. plural: tûto, sîse, atta).

Tolkien stated that it was used only in joining adjectives, nouns, and pronouns in statements (or wishes) asserting (or desiring) a thing to have certain quality, or to be same as another, and also that the copula was not used when the meaning was clear.

[T 54] Otherwise, the copula is left out, which may provide for ambiguous tenses when there is no further context: Quenya allows for a flexible word order because it is an inflectional language like Latin.

[T 62] "Qenya" numerals above twenty show that the smaller units come first, min yukainen "21" being "one-twenty", which reflects how they are written in Tengwar.

[56] Specific rules for consonants were provided in Appendix E of The Lord of the Rings, e.g. the letter c is always pronounced k, qu stands for kw,[T 63] Orqui is Orkwi.

Occasionally, Tolkien wrote Quenya with a "Finnish-style" orthography (rather than the standard Latin-Romance version), in which c is replaced by k, y with j, and long vowels written double.

Other examples include Elendil's words spoken upon reaching Middle-earth, and repeated by Aragorn at his coronation: Et Eärello Endorenna utúlien.

A faulty fragment of the poem "Narqelion", written in early Quenya or Elfin between November 1915 and March 1916, was published by Humphrey Carpenter in his Biography.