Early in the Church's history, the major events in Christ's life were observed with special observances, such as His birth, baptism, death, resurrection and ascension. As these observances developed, a period of time was set aside prior to the major events of Jesus' birth and resurrection as a time of preparation.
During Lent, the Church's worship assumes a more penitential character. The color for the season is purple, a color often associated with penitence. The "Hymn of Praise" is omitted from the liturgy. The word "Alleluia" is usually omitted as well. By not using the alleluia--a joyful expression meaning "Praise the Lord"--until Easter, the Lenten season is clearly set apart as a distinct time from the rest of the year. Additionally, it forms a powerful contrast with the festive celebration of Jesus' resurrection when our alleluias ring loud and clear.
Finally, the penitential character of Lent is not its sole purpose. In the ancient Church, the weeks leading up to Easter were a time of intensive preparation of the candidates who were to be baptized at the Easter vigil on Holy Saturday. This time in the Church's calendar was seen as an especially appropriate time for Baptism because of the relationship between Christ's death and resurrection and our own in Holy Baptism (see Romans 6:1-11). This focus would suggest that the season of Lent serves not only as a time to meditate on the suffering that Christ endured on our behalf but also as an opportunity to reflect upon our own Baptism and what it means to live as a child of God.