A Digital Object Identifier (DOI) is a unique and permanent identifier assigned to a digital items, making it easier to access and cite digital resources. DOIs are often associated with scholarly publications, research data, and other digital assets. They consist of two main components:

Prefix: Assigned by a registration agency (e.g., CrossRef), the prefix specifies the organization responsible for managing the DOI.

Suffix: A unique alphanumeric code assigned by the registrant to identify the specific digital object. 

A typical DOI looks like this: 10.1234/567890

• Example of a DOI in a citation: In this APA example, the DOI was assigned by the publisher, and in this case, Journal of Library Metadata.
  • Green, A. (2021). Metadata application profiles in U. S. academic libraries: A document analysis. Journal of Library Metadata, 21(3-4), 105-143. https://doi.org/10.1080/19386389.2022.2030172