I have often come across floppy disks in the past that were marketed
as “IBM Formatted Floppy.”
What exactly is the meaning of “IBM formatted” and what is the
significance of it?
Despite what some may think, in the past, much software was ported to most of the available platforms (which was a pretty big feat since there were so many back then, but without the benefit of cross-platform, portable code frameworks).
Application programs were often cross-platform, but cross-platform games were even more common. For example, SSI (Strategic Simulations, Inc.) frequently released their games for Amiga, Apple, Atari ST, Atari 400/800, Commodore 64/128, IBM, and occasionally a few other niche platforms.
The boxes would then be marked with the appropriate label indicating which platform the game was for. It would indicate both the format of the binaries as well as the file-system layout of the disk (e.g. FAT12 for IBM and clones, GEMDOS for the Atari ST and Atari DOS for the Atari 400/800, Disk ][ format for Apple II, OFS/FFS for Amiga, CBMFS for C64, etc.)
Figure 1 shows an example of a couple of games available for different platforms with corresponding labels.
And if I format the floppy on my Windows PC, does it still remain “IBM
Yes, Windows (still) uses FAT12 as the default file-system for floppy disks.