TITLE: Complete (possibly official) list of "What is..." articles from the Notices of the AMS
QUESTION [17 upvotes]: Does it exist online and where can one find it? (For example, these two sources are not official; is the longer one complete?)

REPLY [3 votes]: It seems that this is an official (and complete) list
https://www.ams.org/cgi-bin/notices/amsnotices.pl?article_id=whatis&article_type=gallery&gallery_type=whatis