GNU Emacs is an extensible, customizable text editor. Begun in the mid-1970s as TECO, it was re-written using C and Emacs Lisp to provide portability and an extendable interface. It continues to be actively developed today.
Emacs provides context-sensitive editing modes with syntax coloring, is self documenting, has full Unicode support and extensions to do most anything. Die-hard Emacs users do most everything from within Emacs: write code, compile, run, debug, read/compose email, browse the web, do project planning, etc.
For learning Emacs to do work with (La)TeX see the following questions:
- A simpleton's guide to (...)TeX workflow with emacs
- Useful shortcuts or key bindings or predefined commands for emacs+AUCTeX
- A paper by RMS describing the design of Emacs
- The Emacs Wiki, a collaborative wiki for extensions to Emacs
- Wikipedia's Emacs page
- A tour of Emacs
- Emacs FAQ
- History of Emacs and GPL