Updates happen organically, so webmasters won’t have to manually upgrade to take advantage of improvements to the fonts they use. This also means that the fonts on your site may change very slightly over time as refinements are made by type designers and approved by Google, and when Google’s engineers make efficiency improvements using the latest technologies.
Whoa–I’m pretty particular about my typefaces. What’s actually happening on my site when a web font gets automatically updated?
Most of these updates are actually on the engineering side of things; seamless changes that will facilitate general functionality. The API does a bit of processing, and understands each reader’s digital environment; essentially, it can discern what kind of device, browser, and operating system it’s serving. This is a big deal, because Windows machines require fonts with “hinting” data–metadata that improves on-screen rendering–while mobile operating systems don’t. Hinting data can be up to half the file size, and therefore removing it can reduce latency by half. If you’re self-hosting, everyone’s getting the same files, which could have way more info than they actually need; if you’re using the Google Fonts API, the process is totally streamlined, and optimized for each unique system.
We’ve also added and expanded language support over time. For example, with CSS unicode-range, if the font family you use to style comments on your site has new support for the Cyrillic writing system, and a user posts a comment in Russian, their comment will be rendered in the font; the current versions of all browsers will only download the Cyrillic part when needed. You didn’t need to update your site to specify you’d like to accommodate Cyrillic (as you’d have to do when self-hosting)—and your homepage without any Russian text will load just as quickly as before.
And on the design side? Yes, there will be very occasional changes to the look of the fonts offered through the API. However, this is not a bleeding-edge service with daily churn; any given font might get minutely modified once a year (if that), and Google reviews and approves all the changes that type designers make to their projects before going live. For those keen to track, you can ‘watch’ the Github repo
for emails about all update discussions, and/or follow us on Twitter
for a more selective stream of announcements.