Ash Wednesday is the first day of Lent, a solemn Catholic observence marking the start of a 40-day period of prayer, fasting, and repentance leading to Easter, symbolizing believers' mortality ("dust to dust") and need for spiritual renewal through receiving ashes in the shape of a cross on their forehead, often with words like "Remember you are dust, and to dust you shall return". 

The word "Easter" comes from Old English, meaning simply the "East." The sun which rises in the East, bringing light, warmth, and hope, is a symbol for the Christian of the rising Christ, who is the true Light of the world. The Paschal Candle used during the Easter Vigil is a central symbol of this divine light, which is Christ. It is kept near the ambo throughout Easter Time and lit for all liturgical celebrations.

The Easter Vigil is the "Mother of All Vigils" and Easter Sunday is the greatest of all Sundays. The season of Easter is the most important of all liturgical times, which Catholics celebrate as the Lord's resurrection from the dead, culminating in his Ascension to the Father and sending of the Holy Spirit upon the Church. The octave of Easter comprises the eight days which stretch from the first to the second Sunday. It is a way of prolonging the joy of the initial day. There are 50 days of Easter from the first Sunday to Pentecost. It is characterized, above all, by the joy of glorified life and the victory over death expressed most fully in the great resounding cry of the Christian:  Alleluia! All faith flows from faith in the resurrection: "If Christ has not been raised, then empty is our preaching; empty, too, is your faith." (1 Cor 15:14)

"What you sow is not brought to life unless it dies. And what you sow is not the body that is to be, but a bare kernel of wheat, perhaps, or of some other kind;…So also is the resurrection of the dead. It is sown corruptible; it is raised incorruptible. It is sown dishonorable; it is raised glorious. It is sown weak; it is raised powerful. It is sown a natural body; it is raised a spiritual body. If there is a natural body, there is also a spiritual one. So, too, it is written, "The first man, Adam, became a living being," the last Adam a life-giving spirit. But the spiritual was not first; rather the natural and then the spiritual. The first man was from the earth, earthly; the second man, from heaven. As was the earthly one, so also are the earthly, and as is the heavenly one, so also are the heavenly. Just as we have borne the image of the earthly one, we shall also bear the image of the heavenly one." (1 Cor 15:36-37, 42-49)

-USCCB.org