What is an ISBN number or EAN-13 number, and do you need one to list your book on Amazon?

ISBN is the unique identifiers to sell your books online. it is completely different from EAN even it has 13 digits same as ISBN. You must have ISBN numbers which can be bought from Nelson or other websites. Must have ISBN to sell your products at amazon and any other marketplace. you can have cheaper ISBN numbers to sell at amazon from https://codesforamazon.com/product-category/barcodes/isbn-numbers-for-books/