It's a re-write of the Insidious Big Brother Database ([[https://savannah.nongnu.org/projects/bbdb/][BBDB]]) using Emacs Lisp's (relatively new) object oriented libraries. The "E" is vaguely meant to signify "[[https://ericabrahamsen.net/tech/2016/feb/bbdb-eieio-object-oriented-elisp.html][EIEIO]]".
It lives in both the ELPA repositories, and on Github at https://github.com/girzel/ebdb. It's best to [[https://www.emacswiki.org/emacs/InstallingPackages][install from ELPA]], but bug reports and pull requests on Github will also be attended to. Alternately, run ~report-emacs-bugs~, include "EBDB" somewhere in the subject line, and cc the maintainer.
More EBDB-related packages are available in ELPA.
See the [[https://github.com/girzel/ebdb/blob/master/ebdb.org#ebdb-manual][manual]] for usage details.