Angels are bodiless, immortal spirits , limited in knowledge and power. Not all God's angels acted angelically, however. Some angels, led by Satan , rebelled against a life of submission, and were cast out of Heaven. These bad angels were sent to Hell and are known as devils. Not all angels are created equal.
Angels have different functions.
Some do nothing but worship their Lord. Others are sent to deliver messages to creatures on earth. Some are sent as protectors of earthlings. Still others are sent to do battle with devils, who are viewed as initiators of evil temptations. Even though angels are spirits and devoid of a physical nature, believers in angels have had no problem depicting and describing them.