What are angels?

Noun
angel (plural angels)
An incorporeal and sometimes divine messenger from a deity, or other divine entity, often depicted in art as a youthful winged figure in flowing robes.

An angel is a supernatural, immaterial or spiritual being, foun in various religions and mythologies. Their usual role is that of asisting God, acting as an intermediary between Heaven and humanity, protecting and guiding human beings. Angels are often organized into hierarchies although such rankings may vary in each religion. Angels can receive names or titles.

Guardian Angel by Bernhard Plockhorst

"'Angel' is the name of their office, not of their nature. If you seek the name of their nature, it is 'spirit'; if you seek the name of their office, it is 'angel': from what they are, 'spirit', from what they do, 'angel'."
"Angels are very important, because they provide people with an articulation of the conviction that God is intimately involved in human life."

The New Testament includes many interactions and conversations between angels and humans. For instance, three separate cases of angelic interaction deal with the births of John the Baptist and Jesus Christ. In Luke 1:11, an angel appears to Zechariah to inform him that he will have a child despite his old age, thus proclaiming the birth of John the Baptist. In Luke 1:26 the Archangel Gabriel visits the Virgin Mary in the Annunciation to foretell the birth of Jesus Christ. Angels then proclaim the birth of Jesus in the Adoration of the shepherds in Luke 2:10.