What is a DOI?
DOI is a digital object identifier. It is a unique set of characters that are attached to a digital object to allow it to be found when you use a DOI resolver (search tool) on the Internet.
Where are they used?
The most common place they are found is on journal articles but they can be attached to any digital object. They were introduced in 2002 so they will often not be assigned to objects created prior to that date.
How do I find them?
For journal articles, go to the PDF version of the article and look in the top left corner of the first page of the article. If available, DOI's will also be in the database record for an article.
2017 update to the DOI
All of the following are currently considered correct APA Style:
* NOTE: this is the new format however, the other two are currently still acceptable. This change was made, in part, to ensure security with https