We have known that Xiaomi has been customizing all of their Android smartphones around the world by shipping them with a custom skin on top of Android OS.
This custom skin has been named as MIUI by the company. Last year, the company released MIUI 8 which was based on Android 6.0.1 Marshmallow which was the latest version of MIUI until now.
Now, the latest version of MIUI has been released by Xiaomi and it is MIUI 9.