Basic Vi Editing - Most used commands

Every developer has heard of 'vi' at least once in their life. That empty screen with a flashing cursos can be a little intimidating at first. After a few attempts of typing your text and nothing is echoed back to the screen, than it becomes really intimidating. :)
To help those out there who want to be able at least to quit vi editing without closing their Terminal window, here are a few tips and basic commands.
The first thing you should know about vi is that it has two modes of operation:

1. Command Mode: This is the vi starting mode, and you can enter it any time by simply typing 'ESC'
2. Edit Mode: To enter this mode it is necessary to type one of the editing commands while in 'command mode'

And this is a very very short list of vi's useful commands:

• vi filename: opens a file called 'filename'in vi
• ESC w: saves the file being edited
• ESC wq: saves the file being edited and quits vi
• ESC q: quits vi
• ESC q!: quits vi even if there are unsaved changes in the file
• i: insert text before cursor
• I: insert text at beginning of current line
• a: append text after cursor
• A: append text to end of current line
• o: open a new line below the cursor for editing
• O: open a new line above the cursor for editing
• r or c: replace/change single character under cursor
• cw: change current word with new text
• x: delete single character under cursor
• Nx: delete N characters, starting with the one under cursor
• dw: delete a single word
• D: delete the remainder of the line
• dd: delete entire current line
• /string: search forward for occurrence of 'string' in text
• ?string: search backward for occurrence of 'string' in text
• n: move to next occurrence of string
• N: move to next occurrence of string in the opposite direction
• CTRL G: provides line information at bottom of screen

.... or you could simply type man vi in the command line next time! ;)
Note: all these commands also work on vim (Vi IMproved).