Emacs
An extensible, customizable, free/libre text editor — and more.
At its core is an interpreter for Emacs Lisp, a dialect of the Lisp programming language with extensions to support text editing.
Wiki
Manual
Tutorials
C-h t
(Emacs Interactive Tutorial Command)- GNU - Emacs Tour
- TLDP - Beginner's Guide
- ErgoEmacs - Tutorial
Self Documentation
C-h k
(Keybinds)C-h f
(Functions)C-h v
(Variables)