Easter Sunday marks the end of the 40 days of Lent. Good Friday, Holy Saturday, and Easter Sunday are often referred to as the Easter Triduum - (Triduum is a Latin word meaning three). Easter Sunday marks the resurrection of Jesus. All three days are 'moveable feasts' meaning they do not occur on fixed dates in the Gregorian calendar.
Following the crucifixion, Jesus' body was cut down from the cross and buried in a cave. On Easter Sunday, three women visited the tomb but Jesus' body was not there. Jesus was seen by many people on that day and the days which followed. Followers soon realized God had raised Jesus from the dead.
Religious celebrations to mark the resurrection of Jesus include decorating churches with flowers and singing hymns and songs. Easter celebrations have also extended beyond the church. Commercially, Easter is a significant period in many western countries. Egg races, egg hunts, egg painting and egg eating (chocolate ones!) have become popular ways to celebrate Easter and originate from Pagan traditions which marked the arrival of spring.