Q. What is a DOI and how do I use them in citations?

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. Think of it like a Social Security number for the article you’re citing — it will always refer to that article, and only that one.

Source: https://library.uic.edu/help/article/1966/what-is-a-doi-and-how-do-i-use-them-in-citations