Angels (Arabic: ملائكة, Malaekah) in Islam are light-based creatures, created from light by God to serve and worship Him. 
Believing in angels is one of the six Articles of Faith in Islam, without which there is no faith. The six articles are belief in: God, His angels, His Books, His Messengers, the Last Day, and that predestination, both good and evil, comes from God.
Koran, Chapter 17. Al-Isra verse 95. [Isra, The Night Journey, Children of Israel]
"Say, 'If there were settled, on earth, angels walking about in peace and quiet, We should certainly have sent them down from the heavens an angel for a messenger.'"
Attributes of angels
Angels are intangible, sentient entities, who do not possess free will. They were created for the sole purpose of serving God. Being made of light, they can assume almost any form, completely real to the human eye, and traverse a distance as fast as light or faster.
Iblis (Satan/Diabolis/Devil) is a jinn who worshipped God so much that God had raised him to heaven and he used to worship God in the company of the angels. In sharp contrast to Judaism and Christianity in which he is a (fallen) angel, Islam does not recognise the concept of fallen angels. Angels in Islam do not have free will, therefore they cannot disobey God.
When God created Adam from clay (earth) and breathed life into Adam and commanded all present to recognize Adam, Iblis arrogantly defied on accepting Adam as khalifa on earth and disobeyed God stating that he was made from fire and therefore much superior to Adam who is made from clay. Then God had him dismissed from his position in heaven. Shayateen are jinns and men that also arrogantly defy Adam's position as khalifa on earth and disobey God. Both of them possess free will so they can obey or openly defy God.
There is no standard hierarchical organization in Islam that parallels the division into different "choirs" or spheres, as hypothesised and drafted by early medieval Christian theologians. Most Islamic scholars agree that this is an unimportant topic in Islam, especially since such a topic has never been directly mentioned or addressed in the Qur'an. However, it is clear that there is a set order or hierarchy that exists between Angels, defined by the assigned jobs and various tasks to which angels are commanded by God.
(Due to varied methods of translation from Arabic and the fact that these Angels also exist in Christian contexts and the Bible, several of their Christian and phonetic transliteral names are listed.)
Gabriel (Jibraaiyl or Jibril in Arabic). Gabriel is the archangel responsible for revealing the Qur'an to Muhammad, verse by verse. Gabriel is known as the angel who communicates with (all of) the prophets.
Michael (Mikaaiyl in Arabic). Michael is often depicted as the Archangel of mercy who is responsible for bringing rain and thunder to Earth. He is also responsible for the rewards doled out to good persons in this life.
Raphael (Israfil or Israafiyl in Arabic). According to the Hadith, Raphael is the Angel responsible for signaling the coming of Judgment Day by blowing a horn and sending out a Blast of Truth. The blowing of the trumpet is described in many places in Quran. It is said that the first blow will destroy everything [Qur'an69:13], while the second blow will bring all human beings back to life again [Qur'an36:51].
Angel of Death (transliteration "Malak al-Maut") (colloquially referred to as Azrael) who along with his helpers is responsible for parting the soul of the human from the body. The actual process of separating the soul from the body depends on the person's history or record of good or bad deeds. If the human was a bad person in life, the soul is ripped out very painfully. But if the human was a righteous person, then the soul is separated like a 'drop of water dripping from glass'. It is also noted that The Angel of Death will look like a terrifying beast or demon for the souls of bad people and will look like 'the most pleasant sight' when he comes for the souls of good people. A common mistake is to think that The Angel of Death is named Azrael. But the Quran never names The Angel of Death but refers instead to "Malak al-Maut" (translates to Angel of Death), and there is no connection in the Qur'an between the name Azrael and The Angel of Death.
The Qur'an also mentions angels who are ruling the Hell. A verse stipulates this:
"O you who believe! Save yourselves and your families from a Fire (Jahannam) whose fuel is Men and Stones, over which are (appointed) angels stern and severe, who flinch not (from executing) the Commands they receive from God, but do (precisely) what they are commanded."At-Tahrim 66:6
Also the number of Angels of Fire mentioned as Nineteen:
"Over it(Fire) are nineteen (Angels) And We have not made the wardens of the Fire others than angels and We have not made their number but as a trial for those who disbelieve, that those who have been given the book) Tawrat and Bible [may be certain and those who believe may increase in faith and those who have been given the book and the believers may not doubt and that those in whose hearts is a disease and the unbelievers may say: What does Allah mean by this parable? Thus does Allah make err whom He pleases, and He guides whom He pleases" Qur'an 74:30,31
The Qur'an also mentions that angels have qualities that may be typified by the word wings. Another ayat (verse) stipulates this:
"Praise be to God, Who created (out of nothing) the heavens and the earth, Who made the angel messengers with wings - two, or three, or four (pairs) and adds to Creation as He pleases: for God has power over all things."Fatir 35:1
The preceding sentence does not imply that all angels have two to four wings. Most notably, archangels (namely Gabriel and Michael) are described as having thousands of wings. Tradition also notes that certain angels, created solely for the purpose of praising God, have 70 thousand heads, each with 70 thousand mouths that speak 70 thousand languages solely to sing praises for the Almighty. This type of angel, whose type is nameless, accompanied Muhammad up to Jannah (Heaven) when he received commands from Allah. Instead of riding on an angel, Muhammad rode a creature called a Buraq whose stride spans from horizon to horizon.
Verses in the Qur'an that directly name Angels
Gabriel (Jibreel) and Michael (Mikaa'eel) are mentioned early on the Qur'an in the second sura:
"Say: Whoever is an enemy to Gabriel - for he brings down the (revelation) to your heart by God's will, a confirmation of what went before, and guidance and glad tidings to those who believe - Whoever is an enemy to God, and His angels and prophets, to Gabriel and Michael - Lo! God is an enemy to those who reject Faith." (Al-Baqarah 2:97-98)
Another Angel, Malik is defined in the Qur'an as a being who is the Keeper of the Seven Hells. Malik also translates into "King" from Arabic, so it is assumed that Malik is "King" of Hell. However Malik is not an evil angel, nor a fallen one, a notion Islam rejects, rather Malik is merely doing what he is commanded to do by God.
"They [the people in Hell] will cry: ‘O Malik! Would that your Lord put an end to us!’..." (Az-Zukhruf 43:77)
Two other Angels are also mentioned directly in the Qur'an: Haaroot and Maaroot (OR Harut and Marut).
". . . and such things as came down at Babylon to the angels Haaroot and Maaroot . . ." (al-Baqarah 2:102)
Several Angels, Angel of death Izra'il, Israfil and Nakir and Munkar are not mentioned directly in the Qur'an but are explained further in the Hadiths of Muhammad. They are also mentioned in traditional myths, however, they seldom retain complete originality from the Hadith.