LibKey.io is a focused search tool that uses an article's Digital Object Identifier (DOI) or its PubMed ID (PMID) to search a library's collection.

PMID is a PubMed Unique Identifier, which is a 1 to 8 digit number assigned to records in the database. In a PubMed record, the PMID number is located at the bottom left of the record. Yet some citation styles include the PMID near the end. 

For example:

On the other hand, DOI is a unique ID that correspond to an electronic document such as an electronic journal article. Some citation styles include the DOI at the end of the citation.

For example:

You can type the DOI or PubMed ID into LibKey.io, and it'll quickly determine if the full text is available in our library. It's like a shortcut to check for article access without sifting through database search results.