Quick, do an experiment: Whip out your phone and take a short video. Trees outside your window, the other people in line with you, whatever.

Now here’s a question: How did you shoot it? Did you hold the phone sideways, to get a horizontal, or landscape, shot? Or did you hold it vertically? Odds are you held it upright, which means you’re helping to accelerate one of the most underappreciated shifts in the mediascape.

Before 1930, moving picture aspect ratios were all over the place. But mass distribution requires standardization, so influential filmmakers met in Hollywood that year to talk. They settled on the horizontal shot.

Things pretty much stayed that way for decades—until the 2010s, when the mobile phone began to unravel this consensus. The phone is where we shoot our video and, increasingly, view it. In other words, it’s the studio and the movie theater. Yet studies show we hold our phones vertically 94 percent of the time. No wonder: Holding them sideways violates smartphone ergonomics. It feels weird.

Snapchat has done more than anything else to tilt culture upright. Its users intuited this early and create 3 billion snaps per day, nearly all vertical. Indeed, the platform now requires its big-media partners—from National Geographic to CNN to WIRED—to provide such video for its Discover section. Nor is Snapchat alone; broadcasters worldwide are trying out vertical, because phones are where their audiences, especially in coveted younger demographics, are growing the fastest.

This shift isn’t just changing the aesthetics of video—it’s changing the content. It makes some things easier to shoot and some things harder. Vertical is arguably better than horizontal at capturing personality. A horizontal close-up crops out everything but a person’s face. Vertical, by contrast, captures body language too. “You can see not only their face but also how they move their hands,” says Kim Jansson, a Norwegian broadcast journalist. In this sense, mobile phones are weirdly similar to oil painting portraiture of pre-1500 Europe. “Those frames were all vertical too,” says Adam Sébire, cofounder of Australia’s Vertical Film Festival.

Ah, but vertical video makes it harder to look away from a single, upright subject. It’s difficult to capture several people interacting, or to pan around an environment. Our visual field and our everyday settings—an office, a street—are horizontal. So vertical filmmakers often have to assemble a whole out of many close-up shots. “It’s a whole different style of storytelling,” Sébire says. In other words, vertical loves the individual but struggles with context.

So what type of effects will that predilection—that bias in storytelling—have on our culture? I could spin out some quick hot takes, utopian (we’ll understand people better!) or dystopian (we’ll ignore the world around us!). Of course, horizontal video is hardly vanishing. TV, cinema, and Twitch-style livestreaming are all widescreen. YouTube is still devoutly horizontal, in a way that seems faintly Eisenhower-ian next to Instagram’s squares and Snapchat’s towers. (It’s YouTube, after all.)

More important, the way we use verticality itself is liable to evolve. Media always does. “The very first radio shows were theatrical productions, and the very first TV shows were radio shows ported to TV,” says Nick Bell, VP of content for Snap. It took radio producers and television makers years to figure out the grammar of their new mediums.

For the present, one lesson seems clear: Verticality means immediacy. It’s the aspect ratio of breaking news (courtesy of bystanders) and of social media. We have come to see the now through a vertical frame.

Write to clive@clivethompson.net.

This article appears in the September issue. Subscribe now.