ORCID is a site the lets you create a unique ID for all as an author, so that other authors might find all of your relevant research.
For example, if you are looking for Angela Spencer, and want to find all my papers, You will find out that there are many spencer aj[u] in MEDLINE. To find me, and all my papers (some not indexed in PubMed), you could use my ORCID. https://orcid.org/0000-0001-6233-053X
https://orcid.org/about/what-is-orcid/mission
Please note that the NIH is now requiring all research funded by then must have an ORCID
https://grants.nih.gov/grants/guide/notice-files/NOT-OD-19-109.html