Ordinary Time

Represented by the color Green, ordinary time is the time spent outside of a proper season. There are two periods of Ordinary time; the first takes place in January from the day after Epiphany to the day before Ash Wednesday. The second period is between Pentecost and the start of Advent.

Lent

Represented by the color Violet, Lent is the time leading up to the death of Christ on the cross. This is a more somber period, and it's traditional for members of many churches to give up something (preferably something indulgent) for the duration of Lent. Lent begins on Ash Wednesday and ends on Easter morning. Lent always lasts forty days, not counting Sundays.

Easter

Represented by the color White or Gold, the Easter season is a time of celebration of Christ's resurrection. Obviously this begins on Easter itself; it ends on Pentecost. The Easter season lasts fifty days.

Advent

Represented by the color Violet or Blue, this season celebrates the impending arrival of Christ's birth. Advent begins four Sundays before Christmas and lasts until Christmas Eve. It's popular to use an Advent Wreath to mark the passage of time, but this is optional.

Christmastide

Represented by the color White or Gold, this is the last and the first season on the calendar. This is the 12 days of Christmas: it begins on Christmas and ends on January 6th.