ASIN stands for "Amazon Standard Identification Number," a supposedly more-or-less stable identifier Amazon uses to identify its products. Linking to Amazon was first done via an automatic process called AmazonMatching which had the objective to match an album ID to the corresponding ASIN. Today this can only be done manually by adding an AdvancedRelationship of the AmazonRelationshipType which serves better accuracy. There is a tutorial for HowToChangeCoverArt using this type.
ASINs are basically derived from BarCode
s. If two different ASINs have the same barcode, it makes it really difficult to ship the right product to the right people, so this situation is usually avoided. However, sometimes an ASIN can cover more than one barcode. This might happen to allow a new pressing of the same CD to be shipped to a customer who actually ordered the old one.
The same barcode will generally have the same ASIN in any of Amazon's international Websites. However, usually different versions of the same CD (i.e., differently barcoded jewel cases) will be sold in different countries. For example, if you buy Garbage's debut album in the US you'll buy ASIN B000001OAA, whereas if you buy it in Germany you'll buy ASIN B00013R89W. The track listing is identical, but the barcode on the back will be different. So there may or may not be a 1:1 correspondence between ASINs and MusicBrainz albums, depending on whether you consider these to be the same album or not.
It's probably more accurate to say that there's a 1:1 correspondence between releases and ASINs, but even that's not entirely clear. The same barcoded album may be imported to different countries at different times, or different barcoded albums may be quietly substituted for each other within one "release."
- -- (Same note as on CoverArtSites) Just some thoughts from IRC... Catgroove, Freso, warp, and I discussed ASINs which don't have coverart, and whether they ought to be added. Though most supported the practice, catgroove did raise a valid point which bears mentioning. The current use of the ASIN AR is overloaded. It's essentially a "can be purchased for mail order at" AR combined with a "has coverart at" AR, while also being a useful unique identifier that other sites using MusicBrainz data can use to match their data with MusicBrainz data. However, now that Amazon also does 3rd party sales, they increasingly have ASINs which don't pull up art, as the art is user-submitted, not Amazon-created. In these cases, we could link the ASIN for all the other benefits, but then either we then add a coverart AR to get the art from a different source, or we have an ugly empty box show up in the coverart area. Catgroove raised the point that we may be implying a MusicBrainz endorsement of the 3rd party Amazon seller by linking to the Amazon listing for this sort of ASIN, and thus, might be responsible if the purchaser linked from MusicBrainz to the 3rd party via Amazon is unhappy with his/her purchase. --BrianFreud [5/20/2007]