Q&A for How to Get an ISBN Number

Nothing needs an ISBN. ISBNs are used for the convenience of booksellers, libraries, and book distributors, not because they are mandatory.

From what I understand, ISBN is valid worldwide because it's a unique number that can be identified internationally.

It depends on your local and national copyright laws. Contact your national ISBN agency for more information.

Costs pertaining to the ISBN vary from nation to nation. In some countries ISBNs are free, while in others they can only be obtained by paying a fee. Fees are used to pay for administrative costs.

If you're publishing a physical product, you'll likely need a barcode. Consult your publisher and national ISBN agency for more information.

No. A unique ISBN is assigned to each edition and variation of a book. Only reprints share the same ISBN. However, the German and English versions will likely share parts of the ISBN code, depending on how each variation was registered, but the full ISBN number will always be unique.

An ISBN number, is not actually required at all for any publication, as described above.

An ISBN isn't compulsory, but if you want to sell your book or donate it to libraries, then yes, you need one.

No. ISBNs are not required for greeting cards or other ephemera. ISBNs are only required if you want to sell a book.

You don't need a new ISBN if the additional books are just copies of the original book.

Yes, you need a separate ISBN for each format, even though it's the same book.

Wait until you're ready to publish.

Register the name that will hold the copyright.

If the imprint holds the rights to your dad's book, you need to contact a lawyer. If not, it depends on whether you have the copyright and distribution rights. Unless you are certain about that, you should contact a lawyer.

If you definitely have the copyright (e.g. no other great-grandchildren will dispute your right to make money off of it without cutting them in) then yes, but you'll need to get an ISBN.