November 21 is a feast in the Roman Catholic Church dedicated to the Presentation of the Virgin Mary in the Temple.
This event is not mentioned in the Bible, but is present in a few extra-biblical accounts that the Church recognizes.
According to Fr. Alban Butler, there was a custom of some Jewish parents at the time:
Religious parents never fail by devout prayer to consecrate their children to the divine service and love, both before and after their birth. Some amongst the Jews, not content with this general consecration of their children, offered them to God in their infancy, by the hands of the priests in the temple, to be lodged in apartments belonging to the temple, and brought up in attending the priests and Levites in the sacred ministry.
Presentation in the Temple
Furthermore, The Protoevangelium of James, an ancient text from the year 145, provides a story that is a primary basis for this feast:
And the child was two years old, and Joachim said: Let us take her up to the Temple of the Lord, that we may pay the vow that we have vowed, lest perchance the Lord send to us, and our offering be not received. And Anna said: Let us wait for the third year, in order that the child may not seek for father or mother.
And Joachim said: So let us wait. And the child was three years old...And the priest received her, and kissed her, and blessed her, saying: The Lord has magnified your name in all generations. In you, on the last of the days, the Lord will manifest His redemption to the sons of Israel. And he set her down upon the third step of the altar, and the Lord God sent grace upon her; and she danced with her feet, and all the house of Israel loved her.
And her parents went down marveling, and praising the Lord God, because the child had not turned back. And Mary was in the Temple of the Lord as if she were a dove that dwelt there, and she received food from the hand of an angel.
Modern historians continue to debate the authenticity of these documents and whether there was ever a tradition of "Temple virgins" who served the Levites at the Temple in Jerusalem.
For Catholics, this event is not part of the deposit of faith, as it is not contained in the Bible and is not a necessary event for our salvation.
It's certainly possible that Mary lived in the Temple during her childhood, but if she didn't, it wouldn't change anything about our faith.
The key fact is that Mary was a virgin and she conceived Jesus in her womb through the power of the Holy Spirit. That is what we need to know and believe. All of these extra-biblical accounts simply help us ponder what Mary's hidden life was like that is not included in the Bible.