Ordinary Time, meaning ordered or numbered time, is celebrated in two segments: from the Monday following the Baptism of Our Lord up to Ash Wednesday; and from Pentecost Monday to the First Sunday of Advent. This makes it the largest season of the Liturgical Year.

Ordinary Time - Christmas to Lent
The first segment of Ordinary Time focuses on the early life and childhood of Christ, and then on His public ministry.

Ordinary Time - Pentecost to Advent
The second segment of Ordinary Time focuses on Christ’s reign as King of kings, and on the age of the Church. This is the age we live in now, which is the time between the age of the Apostles and the age of Christ’s second and final coming for which we are ever preparing. The final Sunday in Ordinary Time is the Feast of Christ the King; the Saturday after this feast is the final day of Ordinary time.

"Ordinary" Time
Ordinary time does not need to be "ordinary," and is not meant to mean that somehow we get a break from the Liturgical Year. The opposite is true: Ordinary Time celebrates "the mystery of Christ in all its aspects." Many important liturgical celebrations fall during Ordinary Time, including, Trinity, Corpus Christi, All Saints, the Assumption of Mary, and Christ the King. In addition, the Church continues to celebrate Saints days and other events such as The Octave of Christian Unity.

The major feasts, when occurring on a Sunday, trump the regular Ordinary Time Sunday lessons and liturgy. We also may remember and celebrate the parts of Jesus' life that were ordinary, much like our own lives. The color of green is appropriate because it is the most ordinary color in our natural environment.