This sequence of characters assigned to an online article provides a persistent link to a published online article. Each persistent link provides
Why do you need to know?
A DOI is required by some citation styles (APA, Chicago, MLA 8th ed.)
For more information visit, the Digital Object Identifier System.
In RefWorks, if you're NOT sending the citation from a database, but creating a new one, this is how you include a DOI: