The Catechism in Questions & Answers

76. What is the task of the angels?

It is the task of the angels to worship God, fulfil His commissions, and thereby serve Him.
God’s love for human beings is also revealed in that he allows angels to serve human beings. From Matthew 18: 10 we may even conclude that children have special angel protection.

“I am Raphael, one of the seven holy angels, which present the prayers of the saints, and which go in and out before the glory of the Holy One. [...] For not of any favour of mine, but by the will of our God I came; wherefore praise him for ever.”
Tobit 12: 15, 18
“Take heed that you do not despise one of these little ones, for I say to you that in heaven their angels always see the face of My Father who is in heaven.” Matthew 18: 10