Enlarge / iPhones running iOS 16. (credit: Apple)
Apple has released iOS 17 and iPadOS 17 (and their first minor patch, version 17.0.1) to the public this week, and by most accounts, it's a fairly mild and stable update that doesn't seem to be breaking much. But a few years ago, as you might recall, Apple made a change to how it handles operating system transitions—iOS 16 will keep getting updates for a short stretch so that people who want to wait a bit before they upgrade can do so without missing important security updates.
The iOS and iPadOS 16.7 update covers all devices that could run version 16, including older stuff like the iPhone 8, iPhone X, and first-gen iPad Pro that can't be upgraded to version 17. In a couple of months, if precedent holds, newer devices will have to upgrade to keep getting security fixes, while iOS 16 updates will continue to support older devices for at least another year.
On the Mac side, Apple continues releasing security updates for operating systems for two years after they're replaced by a new version. For the last year, that has meant that versions 11, 12, and 13 (Big Sur, Monterey, Ventura) have all been getting patches. Now that version 14 (Sonoma) is around the corner, version 11 will stop being updated.