The Amazon Standard Identification Number (ASIN) is a product identification number used by Amazon.com and its partners. Despite the name, it is not a "standard" outside of Amazon.com, but is used consistently for referencing products within the Amazon network of sites. The words "Amazon Standard" should therefore be read as "standard internal to Amazon", rather than "external standard initiated by Amazon".
Each product sold on Amazon.com is given a unique ASIN. For books with an ISBN, the ASIN and the ISBN are the same. However, owing to the fact that new ISBN-13 numbers will be issued, this is likely to change. Books without an ISBN and other products are also assigned ASINs. ASINs are also used for other items used by Amazon.com (and subsidiaries), such as businesses in the yellow pages (on A9.com) and OpenSearch feeds.
On Amazon's USA-targeted web site, a product's Web address (URL) always contains its ASIN in the format of:
http://amazon.com/gp/product/ASIN-VALUE-HERE
The former format was http://amazon.com/exec/obidos/tg/detail/-/ASIN-VALUE-HERE.
Therefore the URL on Amazon for the paperback of Strunk, White, and Roger Angell's The Elements of Style, 4th Edition, whose ISBN is 020530902X, is:
http://amazon.com/gp/product/020530902X
A shorter form of the URL for most products is:
http://amazon.com/o/ASIN/ASIN-VALUE-HERE
An even shorter form of the URL is:
http://amazon.com/dp/ASIN-VALUE-HERE (dp="detail page")
So the URL for Elements of Style, 4th Edition would become:
http://amazon.com/o/ASIN/020530902X
Similar URLs can be constructed for Amazon sites in other countries, such as:
http://amazon.co.uk/o/ASIN/020530902X
http://amazon.de/o/ASIN/020530902X
http://amazon.fr/o/ASIN/020530902X
However, not all sites carry all titles — e.g. ASIN 393206402X is only available on the German version of Amazon.