Google is making sure manufacturers of devices using Android OS and Google's Play Services is on the same page when Android 11 rolls out by making seamless updates a must-have.
Seamless updates are pulled off by the use of an A/B partition setup, meaning the device has two copies of its important read-only partitions. What that means for you is that you can install major updates on your device and use it as normal while those updates are taking place. It also acts as a backup should anything go wrong. This has been a thing for a number of years now, first getting introduced with Android 7.0 Nougat, but with Android 11 it looks like it's going to be a mandatory requirement for manufacturers of Android devices.
The idea behind seamless updates is that more people are likely to install them, rather than putting it off because they'll have to experience some downtime. It also acts as a recovery mechanism in case an update buggers up. Companies that have already adopted this include Google, Nokia, Motorola, and OnePlus, while Samsung is amongst those who haven't taken up the option off their own back.
A potential downside of the A/B partition is that it requires more storage space because all of the important bits are duplicated, and as Google's requirements will apply to budget phones with storage options on the more paltry side, not everyone is going to be thrilled. [GSMArena]