The spirit Iblis is a Jinn. Iblīs, in Islam, the personal name of the devil, probably derived from the Greek diabolos. Iblīs, the counterpart of the Jewish and Christian Satan, is also referred to as ʿadūw Allah (enemy of God), ʿadūw (enemy), or, when he is portrayed as a tempter,  ash-Shaytan (demon).

The Jinn are ruled by the one true God  who created them more than 25,000 years ago. The Jinn were created from the “searing desert wind” – called Simoon – and are subject to the same universal laws of Islam that mankind must adhere to; the Jinn are also sent prophets bearing God’s message. However, 25,000 years ago the Jinn began to disobey God because they believed themselves to be self-righteous. For that reason, God sent his to destroy them.

It was during this battle that Iblis was recognized from amongst the Jinn by God as “a worthy pupil.” Iblis was brought to heaven by God where he was instructed by the Angels, and, in turn, as he matured Iblis began preaching to the Angels. But, when God created Adam (Adem), Iblis refused to pay homage; and, therefore, God condemned Iblis to hell; however, God also granted Iblis “a stay of execution” until the final day of judgment.

At this time the Jinn regrouped on an island in the “Southern Ocean” and formed their own ‘nation’. Iblis left Heaven and rejoined them as their “king;” he had a second name: Azazil. Iblis's final day of reckoning will come, but until that day comes he reigns as king of the Satans ("shaytans”) who tempt mankind on earth. Although he is evil, Iblis is not the Lord of Evil; and, although fallen from Heaven, he is not a fallen Angel. Rather, Iblis is a "Satan"

'The throne of Iblis is upon the ocean and he sends detachments (to different parts) in order to put people to trial; and the most important figure in his eyes is one who is most notorious in sowing the seed of dissension (between a husband and wife).'

Iblīs has long been a figure of speculation among Muslim scholars, who have been trying to explain the ambiguous identification of Iblīs in the Qurʾān as either angel or jinnī, a contradiction in terms, as angels are created of light (nūr) and are incapable of sin, while jinn are created of fire (nār) and can sin. Traditions on this point are numerous and conflicting: Iblīs was simply a jinnī who inappropriately found himself among the angels in heaven; he was an angel sent to Earth to do battle with the rebellious jinn who inhabited the Earth before man was created; Iblīs was himself one of the terrestrial jinn captured by the angels during their attack and brought to heaven.

In the Qur’an, the Devil has two names. Iblis, probably derived from the Greek diabolos and used always in the singular and as a personal name, usually in the context of his fall from grace. Some scholars have argued that Shaytan, his other name which is Arabic and possibly derived from the roots ‘to be far from’ or ‘born with anger,’ may have been acquired as a result of his rebellion, while others argue that Iblis is used in context of the Devil’s relationship to God, while Shaytan is used in relation to humans. Shaytan occurs much more frequently in the Qur’an than Iblis, usually in connection with the temptation and seduction of humans.

The Qur’an mentions the account of the fall of Iblis several times. When Allah created man, he told all spirits to bow before him. Iblis refused claiming he was better than humans because he was created out of fire instead of mud. Allah then cast him down for his pride. Allah then agrees to let Iblis tempt humanity until the last day when the dead are raised, but tells Iblis he will have no power over Allah, Himself, or any of Allah’s servants. Two of the accounts are listed below:

‘And We created you, then fashioned you, then told the angels: Fall ye prostrate before Adam! And they fell prostrate, all save Iblis, who was not of those who make prostration. He said: What hindered thee that thou didst not fall prostrate when I bade thee ? (Iblis) said: I am better than him. Thou createdst me of fire while him Thou didst create of mud. He said: Then go down hence! It is not for thee to show pride here, so go forth! Lo! thou art of those degraded. He said: Reprieve me till the day when they are raised (from the dead). He said: Lo! thou art of those reprieved. He said: Now, because Thou hast sent me astray, verily I shall lurk in ambush for them on Thy Right Path.’ – AL A’RAAF 7:11-16

‘And (remember) when We said unto the angels: Fall prostrate before Adam, and they fell prostrate, all save Iblis. He was of the jinn, so he rebelled against his Lord’s command. Will ye choose him and his seed for your protecting friends instead of Me, when they are an enemy unto you ? Calamitous is the exchange for evil-doers.’ – AL KAHFI (18:50)

Though Allah had cast Iblis out of heaven, he gave him permission to tempt Adam and Eve before he left. Iblis was the one to persuade Adam and Eve to eat the forbidden fruit. The Qur’an is explicit in saying that the Devil only has the power to tempt, not to compel, for mankind still has its free will to choose to follow Allah or the Devil.

In the name of Allah, Most Gracious, Most Merciful
Mu` meneen Brothers and Sisters,
As Salaam Aleikum wa Rahmatullahi wa Barakatuh.
(May Allah`s Peace, Mercy and Blessings be upon all of you)

Resources:

http://web.uvic.ca/~rpn/files/iblis.html

http://www.britannica.com/EBchecked/topic/280654/Iblis

http://www.deliriumsrealm.com/iblis/

http://www.irfi.org/articles2/articles_3551_3600/who%20is%20iblishtml.htm