An Amazon Standard Identification Number (ASIN) is a 10-character alphanumeric unique identifier assigned by Amazon.com and its partners for product identification within the Amazon organization (summary from <a href="https://en.wikipedia.org/wiki/Amazon_Standard_Identification_Number">Wikipedia</a>'s article).<br/><br/>
Note also that this is a definition for how to include ASINs in Schema.org data, and not a definition of ASINs in general - see documentation from Amazon for authoritative details.
ASINs are most commonly encoded as text strings, but the [asin] property supports URL/URI as potential values too.