Common in:
During the iOS 4 era, users often faced significant hurdles when trying to downgrade their software or install custom operating systems. iTunes would verify the firmware with Apple's servers; if the verification failed, it would throw an error and stop the restore. iREB bypassed this by:
The developer, iH8sn0w, transitioned much of his work to GitHub years ago. You can still find the iREB source code on his official repository, though the tool is largely obsolete for modern iPhones (iPhone 6 and newer) due to changes in Apple's security architecture and the move away from the DFU exploits used in that era.
In the context of software downloads, terms like or "full version" are often added by third-party file-sharing sites to attract clicks. However, iREB has always been a free, open-source utility.