Android 7.0 introduced seamless system updates using the A/B partition model.
The approach keeps the currently running system on one partition while Android downloads and installs an update to a second, inactive partition in the background. After a reboot, the device switches to the updated partition. If the new system fails to boot, it can fall back to the previous working copy, reducing the risk of an unusable phone after an update.
Android 7.0 Nougat introduced the concept and its supporting platform architecture, but the feature was limited to devices designed with the necessary partition layout. Existing phones generally could not gain it through an ordinary software upgrade because their storage was not repartitioned.
Later releases refined the technology. Android 7.1 expanded practical platform support, Android 8.0 added streaming A/B updates, and Android 10 replaced legacy A/B with Virtual A/B. Those later variants can cause confusion, but the original seamless-update feature is conventionally credited to Android 7.0.