What is a DOI?

A DOI ( digital object identifier) is a permanent unique string of letters, numbers, and symbols assigned by a registering agency to an electronic resource.

DOIs can be assigned to articles, books, abstracts, conference papers, etc.  

Since publishers or content owners have to pay to register items, many scholarly articles still lack DOIs. 

More Information: 

• How do I find a DOI?
• How do I cite an article with a DOI?
• How do I cite an article without a DOI?
• How do I find a journal's URL or homepage?
• Learn more in our DOI guide

Do you have other questions about DOIs?  Ask a Librarian!