Emacs 26.2:

  • Emacs modules can now be built outside of the Emacs tree source.
  • Emacs is now compliant with the latest version 11.0 of the Unicode Standard.
  • In Dired, the 'Z' command on a directory name compresses all of its files.

Emacs 26.1:

  • Limited form of concurrency with Lisp threads.
  • Support for optional display of line numbers in the buffer.
  • Emacs now uses double buffering to reduce flicker on the X Window System.
  • Flymake has been completely redesigned.
  • TRAMP has a new connection method for Google Drive.
  • New single-line horizontal scrolling mode.
  • A systemd user unit file is provided.
  • Support for 24-bit colors on capable text terminals.

Emacs 25.2:

- New basic face 'fixed-pitch-serif', for a fixed-width font with serifs. The 'Info-quoted' and 'tex-verbatim' faces inherit from it by default.
- New variable 'use-default-font-for-symbols', for backward compatibility. This variable allows you to get back pre-Emacs 25 behavior where the font for displaying symbol and punctuation characters was always selected according to your fontset setup. By default, Emacs 25 tries to use the default face's font for such characters, if it supports.
- New variable 'inhibit-compacting-font-caches'.
- Using large fonts, at the price of a larger memory footprint.
- The version number of CC Mode has been changed from 5.33 to 5.32.99, although the software itself hasn't changed. This aims to reduce confusion with the standalone CC Mode 5.33 (available from http://cc-mode.sourceforge.net), which is a more mature version than the one included in Emacs 25.2.

Emacs 25.1:

- Emacs can now load shared/dynamic libraries (modules).
- Experimental support for Cairo drawing.
- Enhanced network security (TLS/SSL certificate validity and the like).
- New minor mode 'electric-quote-mode' for using curved quotes as you type.
- Character folding support in isearch.el.
- Xwidgets: a new feature for embedding native widgets inside Emacs buffers.
- New and improved facilities for inserting Unicode characters.

Emacs 24.5:

- A packaging system and interface (M-x list-packages) for downloading and installing extensions. A default package archive is hosted by GNU and maintained by the Emacs developers.
- Support for displaying and editing bidirectional text, including right-to-left scripts such as Arabic and Hebrew.
- Support for lexical scoping in Emacs Lisp.
- Improvements to the Custom Themes system (M-x customize-themes).
- Unified and improved completion system in many modes and packages.
- Built-in support for GnuTLS, GTK+ 3, ImageMagick, SELinux, and Libxml2. 

Emacs 24.3:

- The default X toolkit is now Gtk+ version 3.
- Generalized variables are now part of core Emacs Lisp.
- Updated library that emulate Common Lisp.
- A new version of python.el, which provides several new features.