4.6 What is different about Emacs 26?

• Emacs now provides a limited form of concurrency with Lisp threads.
• Emacs now supports systemd. The new command-line option --fg-daemon is part of this support, it causes Emacs to run in the foreground instead of forking, as under --daemon.
• Emacs now supports 24-bit true color on text terminals which provide that feature. See How do I get colors and syntax highlighting on a TTY?.
• Emacs on X now supports double-buffering, which eliminates display flickering in most situations.
• You can now scroll the Emacs display horizontally using the mouse or touchpad.
• Emacs display now includes an optional feature for display of line numbers via the display-line-numbers-mode command. This feature is much faster than the equivalent display offered by packages such as linum, and also provides many optional features like relative line numbers.
• The automatic horizontal scrolling of the window display when lines are truncated can now optionally be enabled only for the current line, the line where Emacs shows the cursor. Under this mode, all the other window lines are not scrolled to show characters outside of the viewport.
• Letter-case conversions now honor special cases in Turkish and Greek scripts.
• Support for Enchant is now part of the Emacs spell-checking commands.
• Tramp now supports Google Drive filesystems.
• Emacs can now be built while omitting the details of the machine on which it was built, thus making it easier to produce reproducible builds.
• Security vulnerability related to Enriched Text mode is removed. Enriched mode previously allowed saving display properties as part of text; those properties support evaluating arbitrary Lisp code, which opens a vulnerability for Emacs users receiving Enriched Text from external sources. Execution of arbitrary Lisp forms in display properties decoded by Enriched Text mode is now disabled by default.
• Emacs 26.2 comes with data files imported from the latest Unicode Standard version 11.0.0.

Consult the Emacs NEWS.26 file for the full list of changes in Emacs 26.