Where is the address book kept?

I’ve just discovered the joys of the NC Address book and Thunderbird for my wife and I with 2 laptops and 2 static PC’s. I’d like to be able back it up, if at all possible but I don’t see a file for it. Is it kept in the database? If so, is there an easy way to dump it?

Using the search function of this forum, I found this:


Thanks. I tried a search via google for the storage location, but failed to get anything.