Unbricking: If your phone is stuck on the "Nokia" logo or shows a "Phone start-up failed" error.
The Image ROM: This is the core operating system. It usually consists of the MCU (Main Control Unit), the PPM (Post Programmable Memory for languages), and the CNT (Content/Gallery data). Why You Need the RPKG Image ROM
J.A.F. (Just Another Flasher): A popular alternative often used for installing Custom Firmware (CFW). You may need a "PKEY emulator" to run this on modern Windows.