Why is Easter different every year and how is the date determined?

Easter is different every year because it is around the same time as the Jewish festival of Passover which is based on the Lunar Calendar.Ok so how is it the date determined? Well basically Easter Sunday is the first Sunday after the Paschal Full Moon which is the first full moon on or after 21 March. Therefore Easter Sunday can never be earlier than 22 March or later than 25 April.