The season of Septuagesima is a preparation for the season of Lent. The season begins with First Vespers (around 6pm) Saturday, February 12th. The season comprises the Sundays and the weeks they begin of Septuagesima, Sexagesima, and Quinquagesima, as a period of preparation for Lent. The names of these Sundays roughly indicate the time before Easter.
The liturgical color is the violet of penance. Although the liturgical color is one of penance, the Lenten rules of fasting do not bind. The Gloria is omitted on Sundays and ferial days. The Alleluia verse is suppressed, also the word Alleluia verse is replaced by the Tract on Sundays and feast days.
This extended period of preparation is intended to heighten the importance of that for which we are preparing. Michael Fiedrowicz, in his book The Traditional Mass, comments, "With pastoral wisdom and empathy the Church prepares her faithful for the beginning of the season of Lent, which in turn leads into an even more intensified preparation for the feast of Easter with Passion Sunday (fifth Sunday of Lent) before the beginning of Holy Week which culminates in the Triduum Sacrum."