In the Christian world, no other Holy Day can match the importance of Easter Sunday. It is the symbolic day in which Jesus was resurrected thus reuniting His deceased body with His spirit in eternal union. Furthermore, His resurrection marked a reconciliation between God and man thus opening the doors of resurrection for all mankind. The events of the resurrection are found throughout scripture but most prominently in the Gospels (Matthew 28:2-7).
While the feast of Easter was first celebrated in the second century, it wasn't until Constantine called The Council of Nicaea in 325 A.D. that a date was officially pronounced. One debate of that Council was whether the observance of Easter should follow the Jewish custom of holding Passover on a weekday or should be on a Sunday. During this Council, it was decided to hold it on the Sunday following the first full moon after the vernal equinox. Later the date of March 21 was selected as the vernal equinox. Like so many early Christian holidays, the actual day selected for celebration was as much a political decision as it was a symbolic one.
The word Easter is believed to have originated either after the Anglo-Saxon Goddess of Spring, Eostre or the rising of the sun in the east. Even today, many churches have early morning sunrise services on Easter (Luke 24:1). There are other peculiar traditions associated with Easter including the Easter Lily, new clothing, the Easter Rabbit, and the Easter Egg.