Angels are honoured servants created from light. They never disobey Allah and never tire of worshipping Him. Believing in them is the second pillar of Iman.
Jibril brings revelation to the prophets; Mikail is entrusted with rain and provision; Israfil will blow the Trumpet; and the Angel of Death takes the souls.
Noble recording angels (Kiraman Katibin) write our deeds — one on the right for good deeds, one on the left. Guardian angels also protect people by Allah's command (13:11).