The setting of The Hobbit, as described on its original dust jacket, is "ancient time between the age of Faerie and the dominion of men" in an unnamed fantasy world. The world is shown on the endpaper map as "Western Lands" westward and "Wilderland" as the east. Originally this world was self-contained, but as Tolkien began work on The Lord of the Rings, he decided these stories could fit into the legendarium he had been working on privately for decades. The Hobbit and The Lord of the Rings became the end of the "Third Age" of Middle Earth within Arda. Eventually those tales of the earlier periods became published as The Silmarillion and other posthumous works.
In J. R. R. Tolkien's writings, Elves are the first fictional race to appear in Middle-earth. Unlike Men and Dwarves, Elves are immortal, though they can be killed in battle. If so, their souls go to the Halls of Mandos in Aman. After a long life in Middle-earth, Elves yearn for the Earthly Paradise of Valinor, and can sail there from the Grey Havens. They feature in The Hobbit and The Lord of the Rings. Their history is described in detail in The Silmarillion.
Tolkien derived Elves from mentions in the ancient poetry and languages of Northern Europe, especially Old English. These suggested to him that Elves were large, dangerous, beautiful, lived in wild natural places, and practised archery. He invented languages for the Elves, including Sindarin and Quenya.
Tolkien-style Elves have become a staple of fantasy literature. They have appeared, too, in film and role-playing game adaptations of Tolkien's works.
The Dwarves are a race of humanoids shorter than Men, and larger than Hobbits. The Dwarves were created by the Vala Aulë, before the Firstborn awoke due to his impatience for the arrival of the children of Ilúvatar to teach and to cherish. When confronted and shamed for his presumption by Ilúvatar, Eru took pity on Aulë and gave his creation the gift of life but under the condition that they be taken and put to sleep in widely separated locations in Middle Earth and not to awaken until after the Firstborn were upon the Earth. They are mortal like Men, but live much longer, usually several hundred years. A peculiarity of Dwarves is that both males and females are bearded, and thus appear identical to outsiders.
Ents are a species of sentient beings in J. R. R. Tolkien's fantasy world of Middle-earth who closely resemble trees; their leader is Treebeard of Fangorn forest. Their name is derived from an Old English word for "giant". The Ents appear in The Lord of the Rings as ancient shepherds of the forest and allies of the free peoples of Middle-earth during the War of the Ring.
Hobbits are a fictional race of people in the novels of J. R. R. Tolkien. About half average human height, Tolkien presented Hobbits as a variety of humanity, or close relatives thereof. Occasionally known as halflings in Tolkien's writings, they live barefooted, and traditionally dwell in homely underground houses which have windows, built into the sides of hills, though others live in houses. Their feet have naturally tough leathery soles (so they do not need shoes) and are covered on top with curly hair.
Dragons (or "worms") appear in several varieties, distinguished by whether they have wings and whether they breathe fire (cold-drakes versus fire-drakes). The first of the fire-drakes (Urulóki in Quenya) was Glaurung the Golden, bred by Morgoth in Angband, and called "The Great Worm", "The Worm of Morgoth", and "The Father of Dragons".
Trolls are portrayed as monstrously large humanoids of great strength and poor intellect. In The Hobbit, like the dwarf Alviss of Norse mythology, they must be below ground before dawn or turn to stone, whereas in The Lord of the Rings they are able to face daylight.
An orc is a race of humanoid monsters, also called "goblin". In Tolkien's The Lord of the Rings, orcs appear as a brutish, aggressive, ugly, and malevolent race of monsters, contrasting with the benevolent Elves. They are a corrupted race of elves, either bred that way by Morgoth, or turned savage in that manner, according to the Silmarillion.
Tolkien based Quenya pronunciation more on Latin than on Finnish, though it has elements derived from both languages. Thus, Quenya lacks the vowel harmony and consonant gradation present in Finnish, and accent is not always on the first syllable of a word. 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. 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.
Tolkien wrote that he gave Sindarin "a linguistic character very like (though not identical with) British-Welsh ... because it seems to fit the rather 'Celtic' type of legends and stories told of its speakers".
Unlike Quenya, Sindarin is mainly a fusional language with some analytic tendencies. It can be distinguished from Quenya by the rarity of vowel endings, and the use of voiced plosives b d g, rare in Quenya found only after nasals and liquids. Early Sindarin formed plurals by the addition of -ī, which vanished but affected the preceding vowels (as in Welsh and Old English): S. Adan, pl. Edain, S. Orch, pl. Yrch. Sindarin forms plurals in multiple ways.
Tolkien devised Adûnaic (or Númenórean), the language spoken in Númenor, shortly after World War II, and thus at about the time he completed The Lord of the Rings, but before he wrote the linguistic background of the Appendices. Adûnaic is intended as the language from which Westron (also called Adûni) is derived. This added a depth of historical development to the Mannish languages. Adûnaic was intended to have a "faintly Semitic flavour". Its development began with The Notion Club Papers (written in 1945). It is there that the most extensive sample of the language is found, revealed to one of the (modern-day) protagonists, Lowdham, of that story in a visionary dream of Atlantis. Its grammar is sketched in the unfinished "Lowdham's Report on the Adunaic Language".
Rohirric is represented in The Lord of the Rings by the Mercian dialect of Old English because Tolkien chose to make the relationship between Rohirric and the Common Speech similar to that of Old English and Modern English. Tolkien called the language "Rohanese".
Some samples of Khuzdul, the language of the Dwarves, are given in The Lord of the Rings. The explanation here is a little different from the "Mannish" languages: as Khuzdul was supposedly kept secret by the Dwarves and never used in the presence of outsiders (not even Dwarvish given names), it was not "translated" by any real-life historical language, and such limited examples as there are in the text are given in the "original". Khuzdul was designed to resemble a Semitic language, with a system of triconsonantal roots and other parallels especially to Hebrew, just as some resemblances between the Dwarves and the Jews are intentional.
The language of the Ents is briefly described in The Lord of the Rings. As the Ents were first taught to speak by Elves, Entish appears related to the Elvish languages. However, the Ents continued to develop their language. It is described as long and sonorous, a tonal language somewhat like a woodwind instrument. Only the Ents spoke Entish as no others could master it. Even the Elves, master linguists, could not learn Entish, nor did they attempt to record it because of its complex sound structure.
Tolkien devised little of the Black Speech beyond the Rhyme of the Rings. He intentionally made it sound harsh but with a proper grammar. He stated that it was an agglutinative language; it has been likened to the extinct Hurrian language of northern Mesopotamia.
In the fiction, the Black Speech was created by the Dark Lord Sauron to be the official language of all the lands and peoples under his control: it was thus both in reality and in the fiction a constructed language.[18] The Orcs are said never to have accepted it willingly; the language mutated into many mutually unintelligible Orkish dialects, so that Orcs communicated with each other mainly in a debased Westron.