As competitors, Google, Apple, Microsoft, and Adobe are normally hard-pressed to agree with each other, and it’s especially rare when design is involved. But two weeks ago, these four frenemies signed off on a major new standard–one that could revolutionize digital typography. It’s called a variable font.

The new standard is part of an update to OpenType, the most advanced cross-platform standard for scalable computer fonts, which was created by Adobe and Microsoft back in 1996 and which is still used for the vast majority of modern digital fonts. And these so-called variable fonts are designed to be flexible and adaptive within OpenType, aiming to do for digital type design what responsive design did across the web. But what exactly is a variable font? And why are Apple, Google, Adobe, and Microsoft so eager to see them in the wild?

For most people, the words font and typeface are interchangeable, and that’s mostly okay. But to understand variable fonts, we need to get into the weeds a little bit. We tend to think of a “font,” let’s say Helvetica, as being a single design that comes in different weights (bold, italic, thin, compressed, etc.). In actuality, though, Helvetica is a typeface family, which contains numerous different fonts: a totally separate design for Helvetica Bold, another for Helvetica Compressed, and so on.

The problem with this approach is twofold. First, they often look hideous.

On computers, each of these different fonts is essentially a totally different file, which means that if a designer wants to use multiple weights of a single typeface in their app or website, they need to have their users download each one. That increases app file sizes and web load times–so right now, most designers don’t include multiple fonts from a single typeface in their designs. Instead, they rely upon rendering engines to fake it, shrinking, slanting, or blowing up a font according to what’s needed.

For instance, properly bolding letters in a typeface requires a separate bold font to do correctly, but almost all rendering engines are happy to fudge it by smearing a font to be wider, in a process called faux bold. Italics can be faked the same way through slanting. The problem with this approach is twofold. First, they often look hideous. A properly designed bold and italic font is more than just a smeared or slanted copy of a baseline font, with letterforms that are specifically tweaked to be more readable in that format. But besides that, faking different font weights and styles isn’t handled consistently across rendering engines, producing results that look different in, say, Chrome than they do in Firefox.

To sum it all up? Right now, using multiple weights and sizes of a single typeface properly requires a bevy of different, individually loaded fonts, bloating the file sizes of apps and the load times of websites. Computers can fake it, but the results are often gross, and they’re not consistent across platforms and browsers.

So how will variable fonts help fix this problem? Basically, by giving type designers their own version of responsive design: a single font file that can dynamically morph between different weights and sizes as its designer intended while remaining consistent across platforms.