ASIN is Amazon's internal identifier
An Amazon Standard Identification Number (ASIN) is a 10-character alphanumeric identifier used by Amazon to catalog products.
ASINs were designed in 1996 as Amazon expanded beyond books, keeping the 10-character format so existing systems did not need to change.
Why ISBN still matters
ISBNs are the global standard for book identification and are used across retailers, libraries, and distributors.
When you treat ISBN as the master identifier and ASIN as the Amazon-specific counterpart, your catalog stays consistent across channels.
Keep identifiers aligned across formats
When your formats are clearly separated by ISBN, you can map each format to its corresponding ASIN without confusion.
That alignment prevents reporting issues and protects your distribution data.