If you spend any amount of time on social media, the chances are you have probably seen a TikTok video - knowingly or not. In a short space of time, the mobile app used for creating and sharing short videos has become an almost unavoidable part of internet culture. Considering it had amassed more than 500 million users across 150 countries as of November last year, it is easy to see why.

But what exactly is TikTok? Simply put: it is a free, short-form video app popular with teens (or Generation Z, as they are known). It was created in 2016 by ByteDance, a tech company now valued at $75bn (£57.3bn) and based in Beijing, where the app is known as Douyin. In 2017, ByteDance merged with Musical.ly, an enormously popular app built around lipsyncing. Its popularity has since skyrocketed, and it is touted as the first Chinese social media app to make it big in English-speaking countries.

TikTok’s videos – usually 15 to 60 seconds-long and set to music – have flooded social media, occupying a gap once filled by Vine (another beloved, short-form video app, which was shut down by Twitter in 2017). Memes and challenges thrive on TikTok, encouraged by in-app features and celebrities such as Jimmy Fallon, who recently joined the app. Fallon’s #tumbleweedchallenge involved users dropping to the ground and rolling around like a tumbleweed. It may sound weird, but weird is the lifeblood of TikTok – as one Atlantic piece pointed out last year: “Tik Tok is cringey and that’s fine.”

To call the app another Vine is too simple, but in many ways it is what Vine could have been had it stuck around. YouTube is full of TikTok compilations and the funnier videos regularly get uploaded to Twitter as prime retweeting material. Even Facebook – usually one of the slowest social media apps to get in on a youthful trend – can’t escape it.

And, having just passed the 1bn downloads mark, it doesn’t look to be going away any time soon.