Watching clips on Chinese video-streaming sites can be confusing — words in different colors suddenly appear out of nowhere and fly across the screen. This is called "dan'mu" - "Bullet screen" in English. This function is wildly popular among young netizens. It allows real-time comments from viewers to fly across the screen like bullets. The dan'mu messages include jokes and snarky remarks, but also informative explanations. It all serves to help netizens socialize online.