We believe in the existence of the angels of Allah and that they are "honored servants. They do not speak before He does, and they act only by His command" (21:26). Allah created them, and they worship and obey Him. Those who are in His presence do not disdain to worship Him, nor do they weary" (21:19).
Angels are concealed from us, so we cannot see them. Allah may show them to some of His servants. The Prophet Muhammad saw Gabriel in his real shape with six hundred wings that covered the horizons (Bukhari and Muslim). Gabriel took the form of a handsome human being who met Mary and engaged in conversation with her. He came to the Prophet while he was among his Companions in the appearance of an unknown man who did not show any trace of long travel, with very white clothes, and very black hair. He sat facing the Prophet, his knees to the Prophet's knees, peace be upon him, and his palms on the Prophet's thighs and talked with the Prophet. The Prophet later told his Companions that the man they saw was Gabriel (Bukhari and Muslim).
Angels' Functions: We believe that the angels are assigned certain functions. Among the angels is Gabriel, who is entrusted with revelation. He brings it down from Allah to whomever He wishes among His prophets and messengers.
Among them is Michael, who is in charge of rain and the growth of plants; Israfil, who is in charge of blowing the horn at the time of thunder-bolting and the resurrection; the Angel of Death, who takes away people's souls at the time of death. Among the angels is the one who is in charge of mountains; and Malik, the keeper of Hell.
Some angels are in charge of embryos in wombs, others are responsible for protecting human beings, and others are busy recording men's deeds: there are two angels for every person, "when the two angels receive (his deeds), one sitting on the right and one on the left, not a word he utters but by him is an observer ready" (50:18). Some other angels are in charge of questioning the dead after he is placed in his last abode. Two angels come to him and ask him about his Lord, his religion, and his prophet. There "Allah confirms those who believe with the firm saying, in the present life and the hereafter, and Allah leads astray the evildoers and Allah does what He wills" (14:27).
Some angels are in charge of the dwellers of Paradise: "The angels enter to them from every gate, saying: 'Peace be upon you for that you were patient. How excellent is your final home"' (13:24).
The Prophet, peace be upon him, told us that "seventy thousand angels enter or pray in the populous house in heaven every day. They never come back to it as long as they live" (because their turn will never come) (Bukhari and Muslim).