Today is Easter Sunday, the day Christians remember the resurrection of Jesus Christ. Easter is one of the oldest celebrations on the church calendar. It's the traditional day in which Christ's resurrection is celebrated. Christians believe God sacrificed his only son so their sins would be forgiven. Unlike Christmas, Easter isn't celebrated on a fixed day. Instead, Easter falls on the first Sunday after the full moon following the vernal equinox. That could be anywhere from March 22nd until the end of April in a given year.