Fwd: what is fonts:///?

[toyfactory]

Quick question: reading the forum archives about fonts I see the
fonts:///, which I can get to using the file browser, or ctrl-l.  But
where is this folder within the filesystem?  There seem to be a whole
load of font folders on the system - does fonts:/// list the contents of
all the various folders in one virtual folder or something.  If so how
to discover the original locations of the fonts?  Anyone got any quick
answers, or pointers to further reading?

Cheers,

Nick