Angels are intangible, sentient entities, who do not posses 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 just as fast as light or faster.

Angel Gabriel brought Allah's words to Prophet Muhammad and therefore we call Gabriel the Messenger Angel. There are 4 main archangels, as well as several others, each with their own duty.

Each of us has two angels who accompany him. These angels take note of everything we do. They write down our good deeds and our bad deeds. We call these angels the Writing Angels.

There are other angels, too. For example, there is an angel who helps people when they die. This angel brings death, so we call him the Angel of Death.

We cannot see the angels because they are made of things which our eyes cannot see. Angels are created by Allah, just as man and everything else has been created by Him. Angels obey Allah and are His servants, and they never disobey him, so they never commit any sins. They perform many tasks and keep the world in being by obeying Allah's commands.Allah has created Angels out of light and they do not eat or drink, they are characterized by neither feminine or masculine, and they do not tire. Some spend their entire existence in Ruku', others in Sujood. And then when the Judgement is called they will raise their heads and say: Glory be to you, our Lord, we did not worship you in a way befitting your Majesty. We do not know their exact number since there are so many.

Inter-Islam - www.inter-islam.org

Wikipedia - www.wikipedia.org