Angels are pre-adamic God's creatures. they are also called ministering spirits in the bible. why? because they are messengers. they bear God's messages to His elects. they are warring angels also, but much of their activities are not elaborated in the bible except for individuals who try to expand the bible than what it reveals.
there are bad angels too, the fallen ones who rebelled with the first arch angel, Lucifer, now the devil or Satan. these angels are the evil spirits in the air now. also their are loyal angels working day and night for God, the bible is also is silence about their activities except they ministering spirit sent to God's elect. the old testament also showed us on different occasions angelic visitations , it is always to deliver a message e.g Abraham, Jacob, Gideon etc and in the new testament the account of angels is not prominent except in the account of the birth of our Lord Jesus Christ, John the baptist and Paul.
angels are not special creatures in the sense of being worship. it is absolutely wrong to worship an angel. But do you know that the greatest of all God's creature is man. why? only man is created in the image of God and has the ability to receive God and contain God