The Liturgical Year

Solemnities are the highest degree and are usually reserved for the most important mysteries of faith. These include Easter, Pentecost and the Immaculate Conception; the principal titles of Our Lord, such as King and Sacred Heart; and celebrations that honor some saints of particular importance in salvation history, such as Sts. Peter and Paul, and St. John the Baptist on his day of birth.

A feast honors a mystery or title of the Lord, of Our Lady, or of saints of particular importance (such as the apostles and Evangelists) and some of historical importance such as the deacon St. Lawrence.

A memorial is usually of saints but may also celebrate some aspect of the Lord or of Mary. Examples include the optional memorial of the Holy Name of Jesus or the obligatory memorial of the Immaculate Heart of Mary.

Read the full explaination at EWTN.

"Christ yesterday and today… All time belongs to him and all the ages." (Easter Vigil)

The liturgical year consists of a seasonal cycle and a sanctoral cycle, called the Proper of Time and the Proper of Saints, respectively. Both are organized and published in a liturgical calendar, which is also enriched by observances proper to local Churches, whether national, diocesan, parish-level, or religious community. The Paschal Mystery of Jesus Christ—his suffering, death, and resurrection—is continuously proclaimed and renewed through celebrating the events of his life and in the feasts of the Blessed Virgin Mary and the saints.

Liturgical Year

The liturgical year is made up of six seasons:

• Advent - four weeks of preparation before the celebration of Jesus' birth
• Christmas - recalling the Nativity of Jesus Christ and his manifestation to the peoples of the world
• Lent - a six-week period of penance before Easter
• Sacred Paschal Triduum - the holiest "Three Days" of the Church's year, where the Christian people recall the suffering, death, and resurrection of Jesus
• Easter - 50 days of joyful celebration of the Lord's resurrection from the dead and his sending forth of the Holy Spirit
• Ordinary Time - divided into two sections (one span of 4-8 weeks after Christmas Time and another lasting about six months after Easter Time), wherein the faithful consider the fullness of Jesus' teachings and works among his people

The mystery of Christ, unfolded through the cycle of the year, calls us to live his mystery in our own lives. This call is best illustrated in the lives of Mary and the saints, celebrated by the Church throughout the year. There is no tension between the mystery of Christ and the celebration of the saints, but rather a marvelous harmony. The Blessed Virgin Mary is joined by an inseparable bond to the saving work of her Son, and the feasts of all the saints proclaim the wonderful works of Christ in his servants and offer the faithful fitting examples for their imitation.

Each liturgical year begins on the First Sunday of Advent during the preceding calendar year (i.e., the First Sunday of Advent in 2019 began the 2020 liturgical year).

Liturgical Calendar

Saints and other celebrations are distinguished in accordance with the importance assigned to each one: each is a Solemnity, Feast, or Memorial. Sundays and Solemnities begin their celebration on the evening before, Feasts and Memorials are celebrated over the course of one day, and Memorials are either Obligatory or Optional.

Holy days of obligation (also known as feasts of precept) are days when the faithful are obliged to participate at Mass and abstain from unnecessary work or other activities which hinder the suitable relaxation of mind and body. Each Sunday is a holy day of obligation, and six Solemnities are also observed as feasts of precept in the United States.

Finally, there are other days of prayer and special observances throughout the year that are promoted by the Holy See or the USCCB. For the most part, they are not part of the Church's liturgical calendar, but they can help focus the prayers of the Church toward the particular needs of the human family.

From the USCCB website. Read the entirety HERE. 

A pattern in the Church exists where we may focus on an assigned Mystery of Christ each month. This focus gives us a specific aspect of our Faith to meditate on.