Halloween (All Hallows Eve) is a holiday celebrated on the night of October 31st. Traditional activities include trick-or-treating, Halloween festivals, bonfires, costume parties, visiting "haunted houses", and watching scary movies.
 

Halloween originated from a Pagan festival celebrated among the Celts of Ireland and Great Britain to indicate the end of the harvest season. The festival was a time used by the Gaelic culture to take stock of their supplies and to kill livestock in preparation for the long winter months. The Gaelic's believed that on October 31 the boundaries between the living and the dead overlapped and that the dead would come back to life to cause problems like sickness or to destroy the harvest.
 

Nowadays, the mention of Halloween is more associated children (and adults) getting dressed up in costumes. While it has always been a popular holiday in United States, Ireland, Scotland and Canada, it is now celebrated in many other countries around the world.