Emacs

Emacs denominates Article description::a class of powerful, extensible, self-documenting text editors. The original implementation is GNU Emacs, which is still updated today. There's also XEmacs, which was forked from GNU Emacs in the early 1990s. XEmacs is not the X version of Emacs, but a complete separate program.

Available software
Apart from the two big contenders, many lightweight implementations exist, many of which are available in Gentoo:

Ebuild repository
The Emacs project runs an ebuild repository for GNU Emacs and XEmacs (see Project:Emacs/Overlay) which contains a number of packages including many VCS builds. To add the repository:

or

Many more Emacs related packages should now be available for installation.

External resources

 * https://www.gnu.org/software/emacs/refcards/pdf/refcard.pdf - GNU Emacs printable quick reference card (PDF).
 * https://media.emacsconf.org/2019/26.html - Emacs: The Editor for the Next Forty Years by Perry E. Metzger (Video).