Most years someone asks me about the date of Easter and how it is decided each year. The answer:
'The date of Easter Day was defined by the Council of Nicaea in AD325 as the Sunday after the first full moon which falls on or after the Spring Equinox. The Equinox is assumed to always fall on 21st March. In 2009, Easter will fall on April 12th and in 2010, Easter will fall on April 4th.'