Lent is the 40 day period prior to the Sunday Christians acknowledge the resurrection of Christ. During this period, many fast, pray and ponder their spiritual life. Beginning the following day, (Easter Monday) until the Sunday after 50 days from the resurrection,are observed as Eastertide.
This is an celebration of the Holy Spirit coming down on the early believers 50 days after the resurrection. The date is referred to as Ascension Sunday, Whitsunday, or Trinity Sunday. This can be found in Acts chapter 2 in the bible. Eastertide seems predominate in the Roman Catholic church.
I know believers in Christ who say that we should not observe any occasion that is not outlined in the bible. Messianic Jews, and others who believe their views, only acknowledge the feasts and festivals that were celebrated by the children of Israel, and Jesus while He was on the earth.
A former pastor of mine said Jesus followed Jewish custom as He was living during the Old Covenant period. This pastor shared his belief that believers, beginning from the book of Acts are no longer required to follow the letter of the law, which includes sacrifice and resting on the Sabbath.
On the day of Pentecost, the bible says tongues like flames of fire rested upon the heads of those who were waiting together and they began speaking in other tongues/languages. These men and women were also filled with power from above and went forth sharing the gospel and healing the sick.
Today, churches that observe Eastertide may have special services, with awards or presentations of music. Some churches prepare a meal where congregants eat and fellowship together.