Vim

"Vim" is a text editor based on vi. It can be used from the command line or as a standalone application with graphical user interface. The name Vim comes from Vi IMproved.

Installation
Just type.

Modes
Vim got 3 modes:
 * Command mode: Keystrokes are interpreted as commands
 * Insert mode: Keystrokes are interpreted as text (except a few special commands)
 * Visual mode: Visual mode supports you by selecting some text. It behaves a lot like command mode