Halloween

The term has many meanings! Halloween originated from the Pagan festival Samhain, celebrated among the Celts of Ireland and Great Britain. (It is very popular in Ireland!) Irish and Scottish immigrants carried versions of the tradition to North America in the nineteenth century. Other western countries embraced the holiday in the late twentieth century. Halloween is now celebrated in several parts of the western world, most commonly in Ireland, the United States, Canada, Puerto Rico, and the United Kingdom.

Wikipedia has a lot of information about the Halloween holiday.

There is also a Halloween.com website with links to sites that are Halloween-related. There are even some Halloween chats!