GNU Emacs is an extensible and customizable text editor among the most used within the scientific and the software developer communities. The core of GNU Emacs is an interpreter for Emacs Lisp, a dialect of the Lisp programming language with extensions to support text editing.

GNU Emacs is free software and among the features it provides:

  • Content-sensitive editing modes, including syntax highlighting, for several file types (e.g plain text, source code, HTML, ...).
  • Complete built-in documentation, including a tutorial for new users.
  • Full Unicode support for nearly all human languages and their scripts.
  • Highly customizable, using Emacs Lisp code or a graphical interface.
  • A large number of extensions that add other functionality, including a project planner, mail and news reader, debugger interface, calendar, and more. Many of these extensions are distributed with GNU Emacs; others are available separately.