What is different about Emacs 23?

• Emacs has a new font code that can use multiple font backends, including freetype and fontconfig. Emacs can use the Xft library for anti-aliasing, and the otf and m17n libraries for complex text layout and text shaping.
• The Emacs character set is now a superset of Unicode. Several new language environments have been added.
• Emacs now supports using both X displays and ttys in the same session (‘multi-tty’).
• Emacs can be started as a daemon in the background.
• There is a new NeXTstep port of Emacs. This supports GNUstep and Mac OS X (via the Cocoa libraries). The Carbon port of Emacs, which supported Mac OS X in Emacs 22, has been removed.
• Directory-local variables can now be defined, in a similar manner to file-local variables.
• Transient Mark mode is on by default.

Other changes include: support for serial port access; D-Bus bindings; a new Visual Line mode for line-motion; improved completion; a new mode (‘DocView’) for viewing of PDF, PostScript, and DVI documents; nXML mode (for editing XML documents) is included; VC has been updated for newer version control systems; etc.

Consult the Emacs NEWS.23 file for the full list of changes in Emacs 23.