Halloween, also called All Hallow's Eve, occurs on the eve of the Western Christian celebration of All Hallow's or All Saints Day - a day set aside to honor all the Saints of Christendom. Halloween is also a popular celebration with ties to the Celtic festival of Samhain, a celebration of the end of the harvest. The name Halloween comes from the longer name 'All Hallow's Eve'. In the US, this is a popular holiday for young and old and involves dressing up in costumes, harvest parties, and 'trick or treating'. It is celebrated every year on the 31st of October.