Bamboo stems filled with gunpowder that were burnt to create small explosions were once used in ancient China to drive away evil spirits. In modern times, this method has eventually evolved into the use of firecrackers during the festive season. Firecrackers are usually strung on a long fused string so it can be hung down. Each firecracker is rolled up in red papers, as red is auspicious, with gunpowder in its core. Once ignited, the firecracker lets out a loud popping noise and, as they are usually strung together by the hundreds, the firecrackers are known for their deafening explosions that are thought to scare away evil spirits. The burning of firecrackers also signifies a joyful time of year and has become an integral aspect of Chinese New Year celebrations.