Where did the tradition of halloween come from?

The history of Halloween - how it all started. Halloween began as the festival of Samhain. It was part of the ancient Celtic religion in Britain and other parts of Europe. At the end of summer, the Celts thought the barrier between our world and the world of ghosts and spirits got really thin.

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It comes from witchcraft basically, even though it is not the so called correct answer. The most grand practice of witchcraft happens on halloween and it is a day to place generations of curses on people who celebrate it.