If there's a regular bane in Android phone owners' existence, it's the never-ending stream of app updates. Even though they're smaller than full downloads, they still chew up a lot of data -- just ask anyone who has sucked down hundreds of megabytes updating a new phone. Google's engineers have a better solution, though.
They're introducing a new approach to app updates that promises to radically shrink the size of updates with "file-by-file" patching. The resulting patches tend to be about 65 percent smaller than the app itself, and are sometimes over 90 percent smaller. In the right circumstances, that could make the difference between updating while you're on cellular versus waiting until you find WiFi.
The technique revolves around spotting changes in the uncompressed files (that is, when they're not squeezed into a typical app package). Google first decompresses the old and new app versions to determine the changes between files and create a patch. After that, updating is just a matter of unpacking the app on your device, applying changes and compressing it again.
Don't expect to see this when you tap the "update" button, at least not yet. Google is currently limiting the new patching approach to automatic updates, since it needs extra processing power and might take additional time on older hardware. Your brand new Pixel XL should blaze through it, but someone's aging Moto G might take longer. Performance will improve over time, however, so you might well see this expand to all updates once baseline performance is high enough.