The Difference Between "Easter" and "Eastertide"
If asked, most people would say that the celebration of Easter in religious traditions lasts for one day - namely, Easter Sunday. Some may be aware of Good Friday, traditionally the Friday before Easter Sunday, and the day when Christ was crucified. Very few, unless they are religious, will be aware that like Christmas, Easter is more a period of time than a specific day.
Easter is, in fact, a very long period of time. The entire passage of time is best known as Eastertide, which encompasses individual worship days through from Easter Sunday up until Pentecost Sunday and all of the other relatively familiar Easter named days. Eastertide actually lasts for seven weeks rather than a single weekend; more specifically, for seven Sundays. The seventh Sunday is sometimes known as Whitsun, and concludes the Eastertide period.
The most significant worship day to occur during Eastertide is Ascension Day. Scripture says that Jesus was crucified on what is now Good Friday, and was resurrected from the dead on Easter Sunday. He then remained on earth for forty days, before finally departing to take his place in Heaven at the right hand of God on what is now called Ascension Day. During these 40 days between his resurrection and Ascension Day, Jesus spoke with his disciples and informed them of their future roles in his Ministry.
Ascension Day is, as mentioned, exactly 40 days after Easter Sunday. This day, however, is always a Thursday - so many churches postpone the celebrate of Christ's Ascension to the following Sunday, Pentecost Sunday, and conclude Eastertide at this point instead.