 | This help page is a how-to guide. It explains concepts or processes used by the Wikipedia community. It is not one of Wikipedia's policies or guidelines, and may reflect varying levels of consensus. |
A digital object identifier (DOI) is a unique persistent identifier to a published work, similar in concept to an ISBN. Wikipedia supports the use of DOI to link to published content. Where a journal source has a DOI, it is good practice to use it, in the same way as it is good practice to use ISBN references for book sources.
 | It may be better to use other identifiers instead; for example where content is freely available, generally {{PMC}} and {{PMID}} -based links will link to both free content and non-free content, while the DOI links are sometimes only to paywall-restricted content. |