Today is Candlemas, the last "last day of Christmas." (Secular culture, of course, ends its Christmas observance on December 26 or 31; some Christians extend their celebration to Epiphany on January 6, others to the Baptism of Christ on January 13.) While in the post-Vatican II liturgical calendar we have been in ordinary time since the Baptism, today truly provides a final wrap-up of Christmas.
Candlemas, also known as the feast of the Presentation, is a commemoration of the Jewish practice of a purification rite for mothers and new children. Women were considered unclean after giving birth, and had to wait a ritual forty days (in some groups, eighty if the child was female) before returning to the temple.
The family offered a sacrifice of a lamb, two turtledoves, or two pigeons, and the priest said the prayers of purification for the mother. According to the Mosaic law, the firstborn son also had to be offered to The Lord (Numbers 18:15); the purification sacrifice likewise "ransomed" the child from the temple. Although by virtue of the Immaculate Conception Mary was free from impurity, she was still obedient to the law: Mary and Joseph offered their sacrifice in the presence of the priestess Anna, and Simeon offered the prayers for Mary.
We see an echo of Mary's rite of purification in the Church with the churching of mothers, a ritual which has regrettably been largely forgotten in the West but is still observed in most Eastern Catholic and Orthodox Churches.
The name Candlemas comes from the fact that today the priest blesses the candles which will be used in the church over the coming year. A procession with all of the people carrying lighted candles traditionally follows, but this, too, seems to be mostly forgotten in the West.
Today's feast corresponds to the fourth joyful mystery of the rosary, the Presentation of the Christ Child in the Temple. An easy way to mark today would be to say the joyful mysteries instead of the glorious (traditional to Saturday). Singing the Canticle of Simeon, the Nunc Dimitis, would also be appropriate.