ELVES
In J.R.R. Tolkien's legendarium, Elves or are one of the races that inhabit a fictional Earth, often called Middle-earth, and set in the remote past. They appear in The Hobbit and in The Lord of the Rings, but their complex history is described more fully in The Silmarillion. Tolkien had been writing about Elves long before he published The Hobbit.
DWARVES
In the fiction of J.R.R. Tolkien, the Dwarves are a race inhabiting the world of Arda, a fictional prehistoric Earth which includes the continent Middle-earth.
They appear in his books The Hobbit (1937), The Lord of the Rings (1954 – 1955), and the posthumously published The Silmarillion (1977), Unfinished Tales (1980), and The History of Middle-earth series (1983 – 1996), the last three edited by his son and literary executor Christopher Tolkien.
MEN ('MAN')
The Elves call the race of Men Atani in Quenya, literally meaning "Second People" (the Elves being the First), but also Hildor (Followers), Apanónar (After-born), and Fírimar or Firyar (Mortals). Less charitably they were called Engwar (The Sickly), owing to their susceptibility to disease and old age, and their generally unlovely appearance in the Elves' eyes. The name Atani becomes Edain in Sindarin, but this term is later only applied to those Men who are friendly to the Elves. Other names appear in Sindarin as Aphadrim, Eboennin, and Firebrim or Firiath. Being the second born race of Middle-earth, Men are generally weaker than Elves, and have poorer coordination and reflexes.
HOBBITS
Hobbits are a fictional diminutive race who inhabit the lands of Middle-earth in J.R.R. Tolkien fiction.
Hobbits first appeared in the novel The Hobbit, in which the main protagonist, Bilbo Baggins, is the titular hobbit. The novel The Lord of the Rings includes more Hobbits as major characters, Frodo Baggins, Samwise Gamgee, Peregrin Took and Meriadoc Brandybuck, as well as several other minor hobbit characters. Hobbits are also briefly mentioned in The Silmarillion.
According to the author in the prologue to The Lord of the Rings, Hobbits are "relatives" of the race of Men. Elsewhere Tolkien describes Hobbits as a "variety" or separate "branch" of humans. Within the story, Hobbits and other races seem aware of the similarities (hence the colloquial terms "Big People" and "Little People" used in Bree). However, within the story, Hobbits considered themselves a separate race. At the time of the events in The Lord of the Rings, Hobbits lived in the Shire and in Bree in the north west of Middle-earth, though by the end, some had moved out to the Tower Hills and to Gondor and Rohan.
WIZARDS ('ISTARI')
In the fiction of J.R.R. Tolkien, the Wizards of Middle-earth are a group of beings outwardly resembling Men but possessing much greater physical and mental power. They are also called the Istari (Quenya for "Wise Ones") by the Elves. The Sindarin word is Ithryn (sing. Ithron). They were sent by the Valar to help and assist the peoples of Middle-earth to contest Sauron.
ORCS ('GOBLINS')
In J.R.R. Tolkien's fantasy writings, Orcs or Orks are a race of creatures who are used as soldiers and henchmen by both the greater and lesser villains of The Silmarillion and The Lord of the Rings—Morgoth, Sauron and Saruman. The Orcs also work independently as the common antagonists in The Hobbit, though in that work they are more often called Goblins.
Although not entirely dim-witted and occasionally crafty, they are portrayed as miserable beings, hating everyone including themselves and their masters, whom they serve out of fear. They make no beautiful things, but rather design cunning devices made to hurt and destroy.