https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer
https://support.mozilla.org/en-US/kb/categorizing-bookmarks-make-them-easy-to-find

No, bookmarks exported to an HTML file do not contain tags and annotations, so they are lost.

Only a JSON backup preserves the tags.
Note that restoring a JSON backup will replace all current bookmarks.

• http://kb.mozillazine.org/Backing_up_and_restoring_bookmarks_-_Firefox
• http://kb.mozillazine.org/Export_bookmarks

Thanks so much for your answer ... just one quick follow-up question ... where exactly are our bookmarks and tags stored? Are they stored locally, or on Mozilla's website somewhere?

I have put so much time into building my list of tags, it's vital to make sure I don't lose them somehow.

Thanks again for your response, and I look forward to posting this issue as completely resolved !

Sincerely, George

Bookmarks and tags are stored in the places.sqlite file in the Profile folder.

https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data#w_how-do-i-find-my-profile

Thanks !!!