Elves

Elves were an immortal race. They were mostly considered the highest races in all of the Shire, before men took over Middle-earth. They started leaving Middle-earth near the end of the Third Age and by the end of the fourth age, most Elves were gone and men, hobbits and Dwarves inhabited the earth.
About the same time that Varda, Queen of the Valar, ended her labors in creating the Stars, the Elves awoke beside the lake Cuiviénen. The first things they saw were the stars, and henceforth they adored them. The first sound they heard was the flowing of water, and henceforth they loved water as well.
They made speech then, and called themselves the Quendi. Melkor was the first to be aware of them, and he caused evil spirits to go about among them. When one or a small group wandered abroad, they would often vanish. It is believed that Melkor may have created Orcs with the elves he captured.
Oromë, the Huntsman of the Valar, happened upon them when he heard their singing far-off. He was amazed to see them, and called them the Eldar, "People of the Stars". Though at first the Quendi were afraid of Oromë, the noblest among them saw that he was no dark horseman, as the lies of Melkor claimed. He had the light of Aman in his eyes and face, and they were drawn to him. After spending a while among the Quendi, Oromë returned to Valinor and took council with the other Valar and Valier. At the counsel of Ilúvatar, Manwë, King of the Valar, decided that they must go to war against Melkor to protect the Quendi from him, beginning the Battle of the Powers. After a great battle and a siege against Utumno, which reshaped the earth itself, Melkor was bound and cast into the prison of Mandos. Then the Valar, pleased with the outcome, summoned the Elves to Valinor, seeking fellowship with them.
At Oromë's urging, many of the Elves (especially the kindreds of Ingwë, Finwë, and Elwë) agreed. But others, henceforth called the Avari, declared that they preferred starlight and the wide spaces of Middle-earth. So the Elves were first sundered. During the journey to Belegaer, gradually the number of the Elves began to lessen as various groups dropped away. Some of the Teleri (kindred of Elwë) refused to cross the Misty Mountains, and settled in Anduin under the leadership of Lenwë, to be called later the Nandor. Elwë then went missing, and in dismay the rest of the Teleri remained behind, while the Noldor (kindred of Finwë) and Vanyar (kindred of Ingwë) used an island as a ship, and found at last Aman and Valinor.
After several years, Oromë returned to search for the Teleri. Some, under Olwë, relented and followed. Others remained to continue to search for Elwë. Still others, under Círdan, remained because in that time they had become devoted to Ossë and the Sea. Those Teleri that chose to remain were called the Sindar. Elwë, who had fallen asleep due to his enchantment with Melian, returned to claim lordship and establish them in Doriath. The Noldor and some of the Teleri, however, built the great cities of Tirion and Alqualondë (respectively) in Aman. The Vanyar dwelt in Valmar, for they were closest to the Valar of the kindreds.
Melkor, having been released on the promise of good behavior, spread lies about the Valar among the Noldor. Fëanor, the eldest son of Finwë and one of the greatest Elves to have ever lived, hated Melkor more than all the other Noldor, but was paradoxically one of the most influenced by his lies. He forged weapons, and his greatest works, the Silmarils, captured the light of the Two Trees – and his own heart. After Melkor stole the Silmarils and killed Finwë, Fëanor stirred the Noldor to open disobedience to the Valar. In an epic journey filled with treachery, death, and deceit, the Noldor entered in to Exile, crossing over into Beleriand.
The crimes of Melkor in Aman and the subsequent rebellion of the Ñoldor started a centuries-long war that would come to involve all the Elven kindreds of Middle-earth, as well as other races, directly or indirectly. During this time, five great battles were fought against Morgoth and although many were victorious for the elves and their allies, the ultimate result was disastrous. Additionally, the doom that followed the Ñoldor as a result of the Kinslaying at Alqualondë was discovered by Thingol, the King of Doriath and High King of the Sindar. This discovery all but destroyed the relationship between the Sindar and the Ñoldor. There were also other elves and races such as the Petty-dwarves that resented the exiled Ñoldor for usurping their rightful place in Middle-earth.
Though for hundreds of years, the Ñoldor elves fought and endured the forces of Morgoth with little military aid from the other Elven kindreds, a common fear and a common foe allowed for the Elves (especially the Ñoldor) to mingle with mortal Men, who had recently come into the Beleriand from the east. The first of these were the Three Houses of the Edain. They were followed by the Easterlings, some of whom served Morgoth. At first, only the Ñoldor had dealings with Men, as the other elves feared them, but over the generations, men served the Ñoldor and gained their respect. After the Quest for the Silmaril, the blood of the Eldar and the Edain mingled with each other, first through the marriage of Beren and Lúthien, and then through Tuor and Idril. This union would create a bond that would enrich and ennoble both kindreds from then to later ages.
The terrible Oath of Fëanor created strife between the Elven kindreds, as even those not bound were drawn into it over the Silmaril recovered by Beren and Lúthien. The two brothers Celegorm and Curufin attempted to usurp the throne of Nargothrond after the loss of Finrod in the Quest for the Silmaril, but were thwarted by the hound Huan and Orodreth and expelled. It was because of this deed that the Ñoldor of Nargothrond lent little aid to the Union of Maedhros during the Nirnaeth Arnoediad. Twice in the latter half of the First Age, the Sons tried to take the Silmaril from those who inherited it. These acts of cruelty and violence against their Elven kin caused great loss of life and resulted in the deaths of all of them except Maglor, who now wanders the coasts of Middle-earth singing about the suffering of the Ñoldor.
After the destruction of Beleriand in the War of Wrath, the remaining Ñoldor repented of their rebellion and many returned to Eldamar along with some of the Sindar. The Elves that chose to remain in Middle-earth founded peaceful realms. Most of the Ñoldor lived in Lindon with Gil-galad, the High King of the Ñoldor. Hundreds of years later Celebrimbor, the last of the House of Fëanor, founded a new Ñoldorin realm called Eregion. The Sindar joined also with Gil-galad in Lindon and few went beyond the Misty Mountains into Wilderland, becoming leaders of the Silvan Elves in places such as Lothlórien and Greenwood the Great.
The Elven realms flourished for over one thousand years until SA 1200 when Sauron, under the guise of a messenger from the Valar named Annatar, appeared out of the east to offer knowledge to the elves. Gil-galad mistrusted him and barred him from his kingdom. Sauron then approached Celebrimbor and the Elves of Eregion, and against Gil-galad's advice they accepted him and his knowledge.
With Annatar's help, Celebrimbor forged the Rings of Power, but Three Rings alone were made in secret by Celebrimbor and were not directly touched by Sauron's power. Then, Sauron forged the One Ring in order to control the others. The Elves discovered Sauron's plan and took off their rings. Celebrimbor sent the ring Nenya to Galadriel and sent Vilya and Narya to Gil-galad in Lindon.
Furious that the elves had foiled his plans for domination, Sauron demanded the return of the rings and when they refused he prepared for war. For eight years, Sauron laid waste to Middle-earth in his war against the Elves, destroying Eregion and killing Celebrimbor. Eventually, with help of the Númenóreans, Gil-galad was able to lead the elves to victory. Gil-galad then decided to abandon Eregion in favor of the new refuge of Rivendell, formed at the foothills of the Misty Mountains and he made his herald, Elrond, the Lord of Rivendell and his representative in Eriador. Lindon survived still as the greatest kingdom of Elves in Middle-earth. The rest of the Elves of Middle-earth who survived either moved to Lindon, sailed for the West, or continued to live in their lands under caution due to the continued threat from Sauron.
By the latter half of the Second Age, Men continued to spread and grow in Middle-earth. The Faithful from the Downfall of Númenór founded the great kingdoms of Arnor and Gondor. Though Men were set to supplant them in Middle-earth, the Elves were powerful and numerous enough to join with Men one last time to defeat Sauron. Gil-galad led the second greatest host of elves ever seen in Arda and formed the Last Alliance with Elendil, High King of all Dúnedain, and vanquished Sauron in SA 3441.
With the dominion of Men at hand, the Elves became less numerous and more secluded with many becoming wearier of the now mortal lands. Only the realms of Lindon, Lothlórien, and Rivendell survived as havens of Elven bliss. High Elves continued to live in Lindon but most sailed into the West after their king's death along with many Sindar. The last of the High Elves left Middle-earth after the final defeat of Sauron in the War of the Ring.
Elves living in Aman, including those who returned from Middle-earth in the Third and Fourth Ages, lived in a state of blissful happiness as they did before the Revolt of the Ñoldor. Elves that never chose to sail into the Utter West, instead choosing to remain in Middle-earth in places such as the Woodland Realm in the former Mirkwood, would probably become more and more secretive, less numerous, and hidden. Eventually, these lingerers would fade away entirely as their bodies were consumed by the power of their spirits.