Green is used for Ordinary Time and symbolizes eternal life and hope.
Violet is used for Advent and Lent, and symbolizes penance and humility.
White is used for the season of Christmas, the season of Easter, feasts of the Lord other than the Passion; feasts of Mary, the Apostles, the angels, and saints who were not martyrs; All Saints. It symbolizes innocence, purity, and joy.
Red is used for Palm Sunday, Good Friday, Pentecost, and feast days of apostles and martyrs. It symbolizes the Passion, blood, and martyrdom.
Rose is used for Gaudete Sunday (the third Sunday of Advent) and Laetare Sunday (the fourth Sunday of Lent). It symbolizes joy.
Black is used for Masses for the Dead and All Souls Day, and symbolizes sorrow and mourning.
Gold symbolizes what is precious and valuable, plus majesty, joy, and celebration. It also is often used to symbolize the presence of God. It is also sometimes used as a secondary color for other seasons.
Light Blue symbolizes hope and also the sky and heavens. It is increasingly being used during Advent in Protestant churches to distinguish the season from Lent where the traditional purple is also used.