All about Advent

>>>From the USCCB website:

About Advent

Advent (ad-venio in Latin or "to come to") begins the Church year and consists of the four Sundays before Christmas. The Advent season is a time of preparation that directs our hearts and minds to Christ’s second coming at the end of time and also to the anniversary of the Lord’s birth on Christmas. Advent devotions remind us of the meaning of the season. Special Advent Devotions: the lighting of the Advent wreath each Sunday during Advent; the Advent calendar helps remind us of the season with daily thoughts and activities; Advent prayers prepare us spiritually for the birth of Jesus Christ.

Advent Wreath
The four candles represent the four weeks of Advent. Three candles are purple and one is rose. The purple candles in particular symbolize the prayer, penance, and preparatory sacrifices and goods works undertaken at this time. The rose candle is lit on the third Sunday, Gaudete Sunday, when the priest also wears rose vestments at Mass; Gaudete Sunday is the Sunday of rejoicing, because the faithful have arrived at the midpoint of Advent, when their preparation is now half over and they are close to Christmas. The progressive lighting of the candles symbolizes the expectation and hope surrounding our Lord’s first coming into the world and the anticipation of his second coming to judge the living and the dead.

Advent Prayers
Advent prayers call to mind our preparation for the Lord's coming on Christmas and His second coming at the end of the world. The Advent theme of preparing one spiritually requires special Advent prayers focused on waiting, watching, and hoping for the Lord's coming. Many Advent prayer books include daily prayers, while others involve the writings of popular Catholics including Pope John Paul II or Fulton Sheen. Other prayers are meant specifically to be said along with an Advent wreath.

Advent Calendar
The Advent Calendar is believed to have been created in the early 19th century to mark the days of Advent leading up to Christmas. Advent calendars of today usually count down the 24 days of December ending on Christmas Eve. Popular amongst children Advent calendars are a joyful activity that helps children learn about preparing for Jesus' birth. Some Advent calendars have doors to open that reveal some symbol of Advent or Christmas, while others have symbols that are individually placed on the calendar for each day.