Immaculate Conception of the Blessed Virgin Mary is a Holy Day of Obligation on December 8th

In the Catholic Church, the Immaculate Conception of the Blessed Virgin Mary is a holy day of obligation.  Celebrated annually on Dec. 8, it is also the patronal feast day of the United States. The Immaculate Conception is the belief that Mary, the mother of Jesus, was graced by God in such a way that she was preserved from sin from the moment of her existence.  “Immaculate” thus refers to the absence of sin or stain, and “conception” refers to Mary’s beginning. This belief has nothing to do with the sexual manner of Mary’s conception, nor with the way in which she later conceived her own child through the overshadowing of the Holy Spirit (the virginal conception of Jesus).  Rather, it points to God’s graciousness to this woman as she came into the world sinless or “full of grace.”

http://www.dioceseofcleveland.org/immaculate-conception-of-the-blessed-virgin-mary-is-a-holy-day-of-obligation-on-dec-8/