God gives every person a Guardian Angel, who watches over them from their conception until death. The Bible supports this doctrine.
Who are the Guardian Angels?
Jesus said in Matthew 18:10, See that you do not despise one of these little ones, for I say to you that their angels in heaven always look upon the face of my heavenly Father.
The Catechism in paragraph 336 explains that, From its beginning until death, human life is surrounded by the angels’ watchful care and intercession. Beside each believer stands an angel as protector and shepherd leading him to life. Already here on earth the Christian life shares by faith in the blessed company of angels and men united in God.
Local feasts in honor of the guardian angels were first observed in the 1500s.
In 1615, Pope Paul V formally added it to the Roman calendar.