In article , Your Name
wrote:

Many people confuse the Finder's information as being part of the
resource fork, but they are different. The Finder's information is not
stored inside the file at all.

Would you care to explain, then, how the Finder knows what information
to apply to which file?

The Classic MacOS uses information stored within the Finder's own
invisible information files to understand what application to use with
each document file, the three usual ones being "Desktop DB", "Desktop
DF", and "TheVolumeSettingsFolder". These show up under Windows, which
was another cause of confusion for some users.

This is why rebuilding the database was sometimes necessary to fix
minor quirks (such as incorrect icons, especially when creating custom
icons).

somewhat correct. TheVolumeSettingsFolder was unrelated and appeared
long after classic mac os first came out.

MacOS X works in a similar way and has its Finder has different set of
invisible information files to keep track of such things.

no, mac os x definitely does not work in a similar way.