Let’s take a moment to demystify these commonly used acronyms. They are all unique identifiers for an article (like a barcode), which can be used to easily link to or find an article online. The following article has 3 different identifiers assigned to it.
Adeli, Seyed-Hasan et al. “Spirituality in medical education and COVID-19.” The clinical teacher vol. 18,4 (2021): 372-373.
A PMID (such as PMID:33465823) is a unique numerical identifier for an article in PubMed. You will notice every article included in PubMed has a PMID under the citation/abstract. You can search this number in PubMed or in the search box on the IHS Library Homepage to go straight to that particular article.
The International DOI Foundation assigns a unique alphanumeric string to content online known as a Digital Object Identifier or DOI. Most publishers give their articles DOIs because it is the best way to provide links to articles that are persistent or permalinks.
When available, you will also see DOIs included with the citation data in PubMed. In order to “resolve” these DOIs, or make them usable links, simply add http://dx.doi.org/ before the DOIs. Thus, an article with a DOI of 10.1111/tct.13331 can be linked by using http://dx.doi.org/10.1111/tct.13331
Finally, PMCIDs are simply unique identifiers for articles that are included in PubMed Central (PMC). PMC8013884. These numbers will be preceded by PMC first.