When is Easter this year?
That's not an uncommon question. Resurrection Sunday isn't like Christmas, which always falls on December 25th, or Thanksgiving, which always falls on the fourth Thursday of November.
According to ExploreGod, there was a debate over whether to celebrate the special day as marked by the Hebrew calendar, which could put it on any day of the week, or to always celebrate it on Sunday.
According to TimeAndDate.com, as a compromise, the Council of Nicaea in 325 A.D. "established that Easter would be held on the first Sunday after the first full moon occurring on or after the vernal equinox. From that point forward, the Easter date depended on the ecclesiastical approximation of March 21 for the vernal equinox."
If that's not confusing enough, some churches still celebrate Easter based off a different calendar — the Julian as opposed to our more standard Gregorian. Only on occasion do those calendars have an Easter date that coincides.
Whenever you choose to celebrate Easter, the important fact remains that "He is risen! He is risen, indeed!"