Halloween is celebrated around the world with different traditions, such as Día de los Muertos in Mexico and Guy Fawkes Night in the UK. The origins of Halloween can be traced back to the ancient Celtic festival of Samhain and Christian All Saints' Day, as people used to believe ghosts walked the earth on this night. Common activities in the UK include dressing up, bobbing for apples, carving pumpkins, telling scary stories, trick-or-treating, with popular costumes including witches, vampires, skeletons, werewolves, and ghosts.