You can view the available Emacs branches at

http://bzr.savannah.gnu.org/r/emacs/

Development normally takes places on the trunk.
Sometimes specialized features are developed on separate branches
before possibly being merged to the trunk.

Development is discussed on the emacs-devel mailing list.

Sometime before the release of a new major version of Emacs (eg 23.2),
a "feature freeze" is imposed on the trunk.  No new features may be
added after this point.  This is usually some months before the release.

Shortly before the release, a release branch is created, and the
trunk is then free for development.
For example, "emacs-23" for Emacs 23.2 and later, "EMACS_23_1_RC" for
23.1, "EMACS_22_BASE" for 22.x, and "EMACS_21_1_RC" for 21.x.

Consult emacs-devel for exactly what kinds of changes are allowed
on what branch at any time.

If you are looking at this file in a branch other than the trunk,
there may be some branch-specific documentation below this line.
________________________________________________________________________

* elpa

  This branch does not contain a copy of Emacs, but of the Emacs Lisp
  package archive (elpa.gnu.org).  See admin/notes/elpa for further
  explanation, and the README file in the branch for usage
  instructions.