The Digital Object Identifier (DOI) is a unique identifier used to provide a permanent link to any object in the digital environment. They are now issued to all articles by the majority of journals.

Several professional association style guides now specify the use of the DOI when citing journal articles.

For example the APA Style Guide to Electronic References in June 2007 specified the use of the DOI for material accessed online. Where the DOI is not known or unavailable, the URL should be used.

If you have a good reason to remove the DOI from the official style, it is possible to edit the CSL style. See this discussion for more details.