their respective rites. Calendars set aside holy days, such as solemnities which commemorate an event in the life of Jesus or Mary, the saints, periods of fasting such as Lent, and other pious events such as memoria or lesser festivals commemorating saints. Christian groups that do not follow a liturgical tradition often retain certain celebrations, such as Christmas, Easter and Pentecost: these are the celebrations of Christ's birth, resurrection and the descent of the Holy Spirit upon the Church, respectively. A few denominations make no use of a liturgical calendar. Christmas (or Feast of the Nativity) is an annual festival commemorating the birth of Jesus Christ, observed as a religious and cultural celebration among billions of people around the world. Christmas Day is a public holiday in many of the world's nations, is celebrated religiously by a majority of Christians, as well as culturally by many non-Christians, and forms an integral part of the holiday season centered around it. Popular modern customs of the holiday include gift giving; completing an Advent calendar or Advent wreath; Christmas music and caroling; viewing a Nativity play; an exchange of Christmas cards; church services; a special meal; and the display of various Christmas decorations, including Christmas trees, Christmas lights, nativity scenes, garlands, wreaths, mistletoe, and holly. In addition, several closely related and often interchangeable figures, known as Santa Claus, Father Christmas, Saint Nicholas, and Christkind, are associated with bringing gifts to children during the Christmas season and have their own body of traditions and lore. Easter or Resurrection Sunday, is a festival and holiday commemorating the resurrection of Jesus from the dead, described in the New Testament as having occurred on the third day after his burial following his crucifixion by the Romans at Calvary 30 AD. Easter customs vary across the Christian world, and include sunrise services, exclaiming the Paschal greeting, clipping the church, and decorating Easter eggs (symbols of the empty tomb). The Easter lily, a symbol of the resurrection, traditionally decorates the chancel area of churches on this day and for the rest of Eastertide. Additional customs that have become associated with Easter and are observed by both Christians and some non-Christians include egg hunting, the Easter Bunny, and Easter parades. There are also various traditional Easter foods that vary regionally. Religious life Roman Catholic theology enumerates seven sacraments: Baptism (Christening), Confirmation (Chrismation), Eucharist (Communion), Penance (Reconciliation), Anointing of the Sick