If you have one of Google's Pixel smartphones or the Pixel C tablet, or if you have the Nexus 6P or 5X, then you should be able to update to the very latest Android OS version, Oreo 8.1.
Owners of other brands of Android smartphone will presumably, as always, have to wait until the manufacturer makes that version available to carriers, who will then do their tests, after which release of relevant updates can begin to end-users.
Developers have been able to run test versions of Android 8.1 for some time, with the final images now available at the relevant Google Android developer page here.
The information at those two sites, however, is not for the general public, as such, as it is naturally tailored to developers who are writing apps, as you'd imagine.
An Android site I'd never heard of, called The Android Soul, has a more meaningful list of the updates in Android 8.1, which is designed for the everyday user to read and understand.
You'll find all the details, with images, at The Android Soul article, but in short, here are the updates:
- Fixed search bar in Settings app
- Moves is now Gestures in Settings app
- Notifications shade a little transparent
- New setup menu when setting up a brand new phone, factory resetting or booting afresh into Android 8.1
- Navigation buttons dim a little automatically
- Wi-Fi always-on no longer an option
- A new power menu, new recently opened apps
- Bluetooth "pair new device" option lists available devices
- Ringtone selector is now full screen rather than a pop-up
Geeky-Gadgets also lists other bug fixes and improvements, including the fact that Google has fixed the "burger" emoji so the cheese, lettuce and burger meat are now in the "correct" positions.