What is a DOI? A DOI (digital object identifier) is a unique alphanumeric string assigned by a registration agency (the International DOI Foundation) to identify content and provide a persistent link to its location on the internet.
NOTE: It is regarded as the most important part of the citation because it will accurately direct users to the specific article.
Think of it as a "digital fingerprint" or an article's DNA!
The rules for DOIs have been updated in the 7th edition of the Publication Manual of the American Psychological Association. They should be included as URLs, rather than just the alphanumeric string.
Correct:
Incorrect: