Angels are a supernatural thing or it is a spirit.It is said to be like a human being who have wings on their backs and they have halos on their heads.It is found in many religions and also in mythologies. Angelology is known as the
study of the angels.In some of the religions they are told as beings who act in between heaven and earth as a guardian. The main work which are performed by them are mainly taking up the tasks which are given to them by god and fulfilling them properly.Other jobs are of protecting the human being and also leading them into the right path on their lives.
Some of the famous ones who are described in some religion are Michael who is almost like god.Gabriel who helps in giving justice as well as power.Uriel who leads human race to their destiny.Satan brings sins which were done by human being in their life before heavenly court. Metatron is the one who takes care of all the deeds that are happening in earth and heaven everywhere. There is also a hierarchy in case of jewish religion. The overall concept of them are the same in all the religions who accept the fact that there are presence of them with some little differences in them.
In christianity the concept of angels came from jewish who gained it from the egyptians. In the earlier days the christianity had the concept that it is gods messenger but later on came the concepts of the different kinds of angels those are present.In bible also the it is mentioned and they were created as beings for messaging in between god and men.And so angels are being described in islam,zoroastrianism,sikhism,etc.According to contemporary belief also they do exist.