What are Angels?

Angels (Arabic: ملائكة‎ malāʾikah; singular: ملاك or مَلَكْ malāk) are heavenly beings mentioned many times in the Quran and hadith. Unlike humans or jinn, they have no free will and therefore can do only what God orders them to do. An example of a task they carry out is testing individuals by granting them
abundant wealth and curing their illness.Believing in angelsis one of the six Articles of Faith inIslam. Just as humans are made ofclay, and jinn are made of smokeless fire, angels are made of light.

Angels are the obedient, worshipping and chosen servants of Allah. They have ''Noori'' (ethereal, luminous) existence. They are innocent and commit no sin. They do what they are commanded. They neither eat nor drink but subsist on worship and remembrance of Allah.

duties of other angels

All angels have their (respective) assigned jobs. Some angels are posted in paradise and some in Hell. Some record good and bad actions of humanbeings. Some angels develop and shape foetus in mothers' wombs. Some question the dead ones in graves and some torment unbelievers and sinners. Some angels are stationed on the hallowed grave of Allah's choicest Prophet Hazrat Muhammad (may Allah's choicest blessings & peace be upon him) and some convey or carry ''Salaat-o-salaam'' (invocation of Allah's blessings on the Holy Prophet) of the believers and present to the Holy Prophet. Some angels are detailed to attend Islaamic meetings and gatherings where remembrance of Allah is made or ''Meelaad Shareef" is held i.e. where the greatness and excellences of the Holy Prophet are explained.

 the exact number of angels?

Of all creatures of Allah, the angels are the most plentiful. Their exact number is known to Allah Almighty or to His Beloved Prophet (whom Allah has endowed with such knowledge). Their creation is a continuous process. Innumerable angels are created daily. Saints and sages say that the good words and good works of the believers are transformed into angels which take off to the skies, heavens.

Why are the angels called

 Because Allah has created them free of the instinct of committing sins thus they can not disobey Allah. The Prophets of Allah are also innocent like the angels.