Halloween started as a day to mark the end of summer and the beginning of a cold winter. It began roughly 2,000 years ago from an ancient Celtic festival of Samhain.

The idea started out that on this night the world of the living and of the dead merged. Celts were big in mythology so they believed that the spirits of the other world came over and damaged the crops which meant the end of harvest season. To commemorate the event they built huge bonfires and sacrificed crops and animals as sacrifices to the celtic deities. During the bonfire the Celts would dress up in animal costumes.

The Catholics celebrated all of the martyrs on May 13, which they called All Martyrs Day. Over time they also expanded their day and added saints on All Martyrs Day, which they changed the name to All Saints’ Day and to Nov. 1. Over time, Chirstianty spread to the Celts, once this happened the Celts changed the name of All Saint’s Day to All Souls’ Day, to Nov. 2. This day could also be called All-Hallows which eventually changed to All-Hallows Eve, and over time to Halloween.

Halloween came to America when the Pilgrims came but the American Indians also had their own version of the holiday/tradition. Once the Pilgrims came and met the American Indians they combined both of their traditions and new customs to make it an American Halloween.

Over the Centuries, customs and traditions have changed. Now people carve pumpkins, have a sugar rush, dressing up in costume, trick or treating and spend time with friends and families.

Sources- History.com Origin of halloween.