Easter Sunday, is the greatest of all Sundays, and Easter Time is the most important of all liturgical times. Easter is the celebration of the Lord's resurrection from the dead, culminating in his Ascension to the Father and sending of the Holy Spirit upon the Church.
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
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. In a sense, every day of the Octave is like a little Sunday.
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 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.
Liturgical Notes for Easter From Universal Norms on the Liturgical Year and the Calendar:
The first eight days of Easter Time constitute the Octave of Easterand are celebrated as Solemnities of the Lord.
On the fortieth day after Easter, the Ascension of the Lord is celebrated (Thursday, May 26th) except where not being observed as a Holy day of Obligation, it has been assigned to the Seventh Sunday of Easter (May 29th).
The fifty days from the Sunday of the Resurrection (April 17th) to Pentecost Sunday (June 5th) are celebrated in joy and exultation as one feast day, indeed as one "great Sunday." These are the days above all others in which the Alleluia is sung. This sacred period of fifty days concludes with Pentecost Sunday.