For a while, each social media platform had its own identity. YouTube was for clips of TV shows and movies; Instagram was mostly pictures. All these apps grew up alongside the smartphone, with billions of new people coming online for the first time.

Snapchat launched Stories in late 2013 as a way to see what friends are up to. By August 2016, Facebook had copied it almost exactly into Instagram. Kevin Systrom said Snap deserved all the credit for Stories, implying that this was no longer a proprietary feature of a single social network; it was just in the air.

Stories weren't always video, but as cameras and upload speeds improved, video became the dominant medium in many ephemeral spaces. The semi-randomness of Stories made ads less intrusive, seeming more premium due to their full-screen nature.

TikTok combined the vertical-first format with the permanence of YouTube, making it easier than ever to create videos. By defaulting to the For You page, TikTok freed creators from curating profiles or worrying about posting too much. This led to rapid growth and heavy usage among young adults and teens.

The last three years have seen relentless standardization in social media, with these products copying each other at an astonishing pace. The rise of short-form, vertical video has effectively won the internet, making phones our personal TV sets – albeit ones that scroll sideways.