A digital object identifier (or DOI) is a permanent identifier given to a World Wide Web file or other Internet document so that if its Internet address changes, users will be redirected to its new address. A publisher submits a DOI to a centrally-managed directory and then use the address of that directory plus the DOI instead of a regular Internet address. The DOI system was conceived by the Association of American Publishers in partnership with the Corporation for National Research Initiatives , and is now administered by the International DOI Foundation. Essentially, the DOI system is a scheme for Web page redirection by a central manager.

Initially, the only central directory is the one maintained by the DOI Foundation. It is envisioned, however, that other directories might be created and maintained, perhaps by each major industry. A typical DOI might look like:

doi:10.1002/ISBNJ0-471-58064-3

In this example, the "10.1002" identifies the directory and the part after the "/" is the rest of the DOI - in this case, the ISBN number of a particular book that has been published. The "-3" indicates a specific part or chapter in the book.

The DOI can be resolved by making it part of a Uniform Resource Locator (URL) request to the directory. To link to the document in a Web page, one would precede the DOI with the URL dx.doi.org. The example below will resolve to the DOI Handbook:

http://dx.doi.org/10.1000/182

Here, "www.doi.org" happens to be the current and only directory manager. A user clicking on this link would be linking to the directory page which in turn would locate and send back the URL associated with the DOI. Assuming the directory was up-to-date, the page owner and the user could both be sure that the latest page would be returned.

Early users of the DOI system are principally major publishers with thousands of documents to keep track of, many available on the Web. Relocating files from time to time for such a large number of documents would require many link changes on the publisher's site and perhaps a redirection page for users. With the DOI system, any future location change will require only updating the central directory and will not affect other site's links (if they also use the DOI in their link).

See also

• Uniform Resource Name

External links

• Digital Object Identifier Foundation
• CrossRef Organization is a non-profit, independent organization that includes leading publishers from around the world. CrossRef utilises the DOI to resolve links to electronic documents and journal articles.