Today in the Orthodox Church marks when Mary, the Mother of Jesus, (or who the Orthodox call Theotokos) was brought to the temple to live. Just like Samuel had been brought to the temple by his mother Hanna. Actually the story of Hanna and Samuel and Anna (Mary's mother) and Mary are very similar. Joachim (Mary's father) and Anna where old in age and mourned over their bareness. God heard their cry and blessed them with a baby. Anna, upon hearing that she was with child, immediately gave her child over to The Lord, saying whether this baby is a boy or a girl I will bring it as an offering to the house of The Lord and it will serve Him all the days of its life. And this child that they where blessed with was the mother who would contain the Uncontainable in her womb.
Virgin Mary was taken —presented—by her parents Joachim and Anna into the Jewish Temple in Jerusalem as a young girl, where she lived and served as a Temple virgin until her betrothal to St. Joseph. One of the earliest sources of this tradition is the non-canonical Protoevangelion of James, also called the Infancy Gospel of James.
Mary was solemnly received by the temple community which was headed by the priest Zacharias, the father of John the Baptist. She was led to the holy place to become herself the "holy of holies" of God, the living sanctuary and temple of the Divine child who was to be born in her. The Church also sees this feast as a feast which marks the end of the physical temple in Jerusalem as the dwelling place of God.
A great book to read about the Protoevangelion of James is written by Fredricka Mathewes-Green called The Lost Gospel of Mary.