Access date
Also called: retrieval date, date accessed, accessed
The date you viewed an online source, recorded when the content is liable to change or carries no publication date.
An access date is a hedge against instability. APA 7 asks for one only when the content is designed to change and is not archived — a wiki, a live dashboard, a social feed — and explicitly does not want one for a journal article with a DOI. MLA 9 treats it as optional but recommended for undated pages. Chicago wants one for most web sources.
It is not a substitute for a publication date. Where both exist, both go in. And an access date on a stable source with a DOI is noise: the DOI already guarantees the reader gets what you got.
See also
n.d. (no date)The abbreviation used in place of a year when a source carries no identifiable publication date.PermalinkA URL the publisher undertakes to keep working, as opposed to a session, search, or tracking URL that will rot.DOI (Digital Object Identifier)A permanent identifier for a document — usually a journal article — that resolves to its current location no matter how many times the publisher moves it.