Easter is celebrated on the first Sunday after the Paschal full moon, which is the first full moon occurring either on or after the spring equinox (March 21). As a result, Easter will always fall between March 22 and April 25. To get the date for Palm Sunday, we go back one full week since it's the Sunday before Easter Sunday. More @Wikipedia
Hover over any link to get a description of the article. Please note that search keywords are sometimes hidden within the full article and don't appear in the description or title.