ISBN stands for International Standard Book Number. These numbers are used to keep a record of Metadata for all books.
I discovered it would be wise to purchase an ISBN and Barcode for my book, before going to print.
The place to go for Australian ISBNs is Thorpe Bowker. They have all the information on their website to make a decision on how many ISBNs you should purchase, based on your needs. For example if you wish to publish an ebook and hard copy, you will need a separate ISBN for each. Barcodes are needed, especially if you want to approach a book shop to sell your beautiful book, then both of these items are essential.
The prices vary, and I went for 10 ISBNs + 1 barcode, as it was more economical over time, and I hope to self-publish more books!
The process was relatively simple, there are quite a few pages of questions. However, they will answer your queries via email promptly.
Good luck with your writing journeys! I’d love to hear your handy writing tips.