A DOI, or Digital Object Identifier, is a string of numbers, letters and symbols used to permanently identify an article or document and link to it on the web. A DOI will help your reader easily locate a document from your citation.

DOIs (digital object identifiers) are unique alphanumeric codes assigned to each unique article, chapter, book, or other publication by publishers who cooperate in using the DOI standard. You will often find the DOI displayed prominently in the bibliographic information for a publication. DOI names may be expressed as URLs (URIs) through a HTTP proxy server. In addition, DOI is a registered URI within the info-URI namespace (IETF RFC 4452, the “info” URI Scheme for Information Assets with Identifiers in Public Namespaces). See the DOI Handbook, 2 Numbering and 3 Resolution, for more information.