Halloween originated from the Celtic harvest festival celebrating the end of summer. It is now celebrated in the United States on October 31st, where children dress up in costumes and go door-to-door saying "trick or treat" to receive candy. The tradition stems from Celtic practices of carving scary faces into turnips to ward off evil spirits. Black cats also became associated with Halloween, as some believed witches could transform into these animals to go unnoticed. If a black cat crosses one's path on Halloween, it was thought to bring bad luck, but one could counter it by taking seven steps back and cursing.