The APA 7th edition requires publication data for electronic sources. The DOI is the preferred electronic retrieval format because it provides a persistent link to a document’s location on the Internet. If no DOI is available, a URL can be included.
DOI is an abbreviation for digital object identifier. This is simply an ID number assigned to an ‘object’ such as a journal article (or a book). It allows the ‘object’ to be found across any physical location such as a database. Publishers assign it to online articles so that an article may be easily identified and found within the many possible databases in which they may reside.