Sometimes URLs for websites and other online content can change over time. A permalink is designed to not change over time. Therefore, use permalinks whenever possible when citing online materials.
DOIs (digital object identifiers) are a standardized form of permalink. Most online scholarly content is published with a DOI that you can use in your citation.
Read more about how to find DOIs here: https://libanswers.unl.edu/faq/342115
While DOIs are the "standard" type of permalink mentioned in citation style guides, here are other types of permalink you may find while researching:
- handle.net
- perma.cc
- purl.fdlp.gov
- archive.is
- archive.today
- web.archive.org