Registry Editor or RegEdit.exe edit the system registry, which stores information about the system. Different software may choose to write data to the system registry to aid the program. It also contains boot information, including lock picture, safe mode settings, file association settings and more. It appears in every Windows operating system beyond Windows 3.1 and has been a critical component since. In Windows 3.1, it was much simpler and less like the ones on the other Windows versions.