What is Oracle Forms and what is it used for?

Oracle Forms is a 4GL Rapid Application Development (RAD) environment. Forms Builder is used to create applications to enter, access, change, or delete data from Oracle (and other) databases. The Forms Runtime environment is required to execute compiled Forms modules. Forms can also be deployed across the Web using the Oracle [Internet Application Server]] (iAS) Forms Services.

Oracle Forms is part of Oracle's Internet Developer Suite (iDS). Previous versions of it was called SQL*Forms. [edit] Can one convert/reverse engineer a FMX back to a FMB file?

Unfortunately not. One should always backup the FMB files to ensure they are not lost. The best you can do is to open the FMX file in a good text editor and copy most of your SQL out of it. After that, you will have to recreate the form from scratch. [edit] Can an Forms FMX be moved from one operating system to another?

No, FMX files are operating system dependent. On the other hand, FMB's are not. So, you can just copy your FMB files to the new operating system and regenerate them.

PS: You also need to regenerate the FMB files after upgrading to a new Forms version.