The most powerful aspect of the web is also what makes it so challenging to build for: its universality. When you create a website, you’re writing code that needs to be understood by a plethora of browsers on different devices and operating systems. It’s difficult.

To make the web evolve in a sane and sustainable way for both users and developers, browser vendors work together to standardize new features, whether it’s a new HTML element, CSS property, or JavaScript API. But different vendors have different priorities, resources, and release cycles — so it’s very unlikely that a new feature will land on all the major browsers at once.