MIUI is the Android skin overlay on Xiaomi devices. It was widely used across all devices in the early days of Android as a custom Rom. Back in the day if you wanted an iOS experience on your Android phone MIUI was the closest you could get. Today MIUI still thrives. Not only is it the OS of Xiaomi devices, but the developer community still keeps Roms updated for many devices. August 23rd will be the official global rollout for the latest stable version of the rom. MIUI 8 will rollout first to Redmi 1S, Mi 2/2 S, Mi 4i, Redmi Note 3G, Redmi Note 4G with the rest of the scheduled devices receiving the Rom update shortly after.
via MIUI