[BigDiskBitRot]

If you have a lot (like 5 000) of tabs open in the browser, you want to also backup the current browser session, in addition to just the bookmarks.

Using Mozilla Firefox, the easiest way to backup the whole session (saved passwords, bookmarks, open tabs, add-ons) would be to write to Firefox's address bar about:profiles and click Open Main folder button, from there go up one folder level and copy-paste the folder ending in .default to a backup media. To automate this whole process, could be used for example program called Duplicati, it has network backup capabilities.