The ROM packages you can flash on your device come in two formats: **Fastboot ROMs** and **Recovery ROMs**.
**Fastboot ROMs** come in .tgz files, they're around 2GB in size, contain images for nearly all partitions and have flashing scripts for major desktop operating systems. Flashing a Fastboot ROM is very thorough, clean and flashes nearly all partitions on a device.
**Recovery ROMs** come in .zip files, they're lighter and contain images only for the most important partitions. Flashing a Recovery ROM isn't as clean as flashing a Fastboot ROM as it leaves many partitions untouched.
Official MIUI ROMs are available in the forms of [Fastboot ROMs](http://en.miui.com/a-234.html) and [Recovery ROMs](https://c.mi.com/global/miuidownload/index). Recovery ROMs can be flashed using MIUI itself or XiaomiADB, while Fastboot ROMs can be flashed using MiFlash or the Xiaomi ADB/Fastboot Tools and they also need an unlocked bootloader. More info [here](Flash_official_ROMs.md).
