An angel is a bodiless, immortal spirit, limited in knowledge and power. God created angels to worship Him. 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. From top to bottom, the celestial hierarchy includes seraphim, cherubim, thrones; dominions, virtues, powers; principalities, archangels, and angels. 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. Angels, say their advocates, are invisible but can take the form of visible things. Angels are usually depicted with wings and looking like human adults or children. The wings are undoubtedly related to their work as messengers from God, who lives in the sky. The anthropomorphizing is understandable. Depiction enhances belief. But a bodiless creature cannot be depicted. A depiction of a creature of less than human stature would be undignified and unworthy of celestial creatures. Nevertheless, it is puzzling how a bodiless creature thinks and feels. To talk of a spirit as a non-bodily creature seems to be akin to talking of a "round square." Trying to imagine thinking or feeling occurring independently of a body is like trying to imagine the spherical shape of a ball occurring independently of the ball.
Since angels are invisible but capable of taking on visible forms, it is understandable that there have been many "sightings." Literally anything could be an angel and any experience could be an angel-experience. The existence of angels cannot be disproved. The down side of this tidy picture is that angels cannot be proved to exist, either. Everything that could be an angel could be something else. Every experience that could be due to an angel could be due to something else. Belief in angels, angel sightings and angel experiences is entirely a matter of faith.
Even if they exist only in the imagination, however, angels can be very useful. They can serve as monitors of behavior and protectors of children. A parent can try to control a child's behavior by convincing the child that an angel is always watching over him or her. The angel is presented as being a kind of guardian, but the child will hopefully realize that the angel is also keeping track of all deeds, good and bad, even those done when mommy and daddy aren't around. The guardian angel is a comforting and versatile concept, and is the basis for many myths. Much entertainment in books, films and television programs is based on the concept of the guardian angel, often transformed into a superhuman master of occult powers.
Traditional religionists are not the only ones who love angels. New Age mythmakers have made an industry out of angels. Dozens of books connecting angels with everything from guidance in daily life to talking to the dead to psychic healing are published every year. Sales of angel figurines and other material products are brisk. As one lofty soul put it: "Gently guided by angels, we nurture and cherish the creative soul that heals itself."