DOI and CrossRef explained

"DOI: The 'Big Brother' in the dissemination of scientific documentation," by Miquel Termens, does an excellent job of explaining the reasons and organizations behind DOI (Digital Object Identifiers). The article also gives a clear, concise overview of the inner workings of CrossRef.  (CrossRef, as their site explains, "... allows the user to move from one article to another at the citation level, regardless of journal or publisher.") I would recommend this article for anyone interested in cross linking or the mechanics of access to scholarly publishing.

Although the article is now 8 years old, not too much appears to have changed, other than how DOI is used in the e-book world. DOI is now typically used for scholarly e-books in much the same way it is used for e-journals:  assigned at both title and chapter level by those scholarly publishers who host DRM-free PDF e-book versions on their sites (e.g. Springer, Elsevier ScienceDirect, Wiley, JSTOR, and others).  In adding book chapter DOIs, publishers can take advantage of reference linking (CrossRef et al.), facilitate user access through index and discovery systems, and allow for limited resource sharing (ILL and scholarly sharing at the chapter level).

This quote from the article illustrates the importance of DOI in the scholarly publishing chain and explains the dismay of everyone involved when administrative error temporarily brought the dx.doi.org domain down earlier this week:

The Handle System offers an additional improvement—the working URL is always operative and does not require maintenance. URL obsolescence, and the consequently large number of broken links, is one of the major problems in present day internet structure and it slows down the allocation of links between websites [10]. Handle System provides a solution because, for each, document, it generates a persistent address, a URN, which can be used to locate it. DOI codes can operate as URNs if they are preceded by an address resolution server, e.g., [http://dx.doi.org/10.1126/science.1088234]; hence, the reader does not need to be concerned about a link’s operating state as this is attended to by the publisher of the referenced journal by maintaining an up-to-date URL in the DOI databases.