Modes
(default)	command mode
i		insertion mode (insert text)
ESC		return to command mode

Quitting
:x	Exit, saving changes
:q	Exit as long as there have been no changes
ZZ	Exit and save changes if any have been made
:q!	Exit and ignore any changes

Inserting Text
i	Insert before cursor
I	Insert before line
a	Append after cursor
A	Append after line
o	Open a new line after current line
O	Open a new line before current line
r	Replace one character
R	Replace many characters

While in Insert mode...
CTRL-w		Deletes previous word
CTRL-x		Deletes to start of inserted text
CTRL-v		Take the next character literally (do not interpret as VI command). 
CTRL-v{TAB}	Example showing insert of Tab character. Ctrl+v{Tab key}
:r file		Reads file and inserts it after current line
:nr file	Reads file and inserts it after line n

Deleting Text
Most deletion commands are performed by typing d followed by a motion. 
For example, dw deletes a word. 
x	Delete character to the right of cursor
X	Delete character to the left of cursor
D	Delete to end of line
dd	Delete current line
dw	Delete word

Changing text
The change command is a deletion command that leaves the editor in 
insert mode. It is performed by typing c followed by a motion. 
For example cw changes a word. A few other change commands are:
C	Change to the end of the line
cc	Change the whole line

Case|Join|Repeat|Undo
~	Toggles upper and lower case. Position cursor over text, then shift-tilde to change its case.
J	Join lines
.	Repeat last text-changing command
u	Undo last change
U	Undo all changes to line

Motion
h	Move left
j	Move down
k	Move up
l	Move right
w	Move to next word
W	Move to next blank delimited word
b	Move to the beginning of the word
B	Move to the beginning of blank delimted word
e	Move to the end of the word
E	Move to the end of Blank delimited word
(	Move a sentence back
)	Move a sentence forward
{	Move a paragraph back
}	Move a paragraph forward
0	Move to the begining of the line
$	Move to the end of the line
1G	Move to the first line of the file
G	Move to the last line of the file
nG	Move to nth line of the file
:n	Move to nth line of the file
fc	Move forward to c
Fc	Move back to c
H	Move to top of screen
M	Move to middle of screen
L	Move to botton of screen
%	Move to associated ( ), { }, [ ]

Yank & Put...

Yanking Text
Yank copies text to memory for put(paste) later.
Most yank commands are performed by typing y followed by a motion. 
For example:
y$	Yank from cursor position to end of the line.
yy	Yank the current line

Putting text
p	Put after the position or after the line
P	Put before the position or before the line

Buffers
Named buffers may be specified before any deletion, change, yank or put command. 
The general prefix has the form "c where c is any lowercase character. 
for example, "adw deletes a word into buffer a. 
It may thereafter be put back into text with an appropriate "ap.

Search for strings
/string		Search forward for string
?string		Search back for string
n		Search for next instance of string
N		Search for previous instance of string

Search & Replace
The search and replace function is accomplished with the :s command. 
It is commonly used in combination with ranges or the :g command (below).
:s/pattern/replace	
		^Search for pattern and replace with string on current line.
:s/pattern/replace/flags
		^Replace pattern with string according to flags on current line.
:%s/pattern/replace/g
		^Replace all instances of pattern on all lines.
:%s/pattern/replace/gc
		^Replace all instances of pattern on all lines, confirm each replacement.
g		Flag=g - Replace all occurences of pattern
c		Flag=c - Confirm replaces.
&		Repeat last :s command
n		Search for next instance of string
N		Search for previous instance of string

Regular Expressions
. (dot)		Any single character except newline
*		zero or more occurances of any character
[...]		Any single character specified in the set
[^...]		Any single character not specified in the set
^		Anchor - beginning of the line
$		Anchor - end of line
\<		Anchor - begining of word
\>		Anchor - end of word
\(...\)		Grouping - usually used to group conditions
\n		Contents of nth grouping

[...] - Set Examples 
[A-Z]		The SET from Capital A to Capital Z
[a-z]		The SET from lowercase a to lowercase z
[0-9]		The SET from 0 to 9 (All numerals)
[./=+]		The SET containing . (dot), / (slash), =, and +
[-A-F]		The SET from Capital A to Capital F and the dash 
		(dashes must be specified first)
[0-9 A-Z]	The SET containing all capital letters and digits and a space
[A-Z][a-zA-Z]	In the first position, the SET from Capital A to Capital Z
		In the second character position, the SET containing all letters

Regular Expression Examples 
/Hello/		Matches if the line contains the value Hello
/^TEST$/	Matches if the line contains TEST by itself
/^[a-zA-Z]/	Matches if the line starts with any letter
/^[a-z].*/	Matches if the first character of the line is a-z and there is at 
		least one more of any character following it
/2134$/		Matches if line ends with 2134
/\(21|35\)/	Matches is the line contains 21 or 35
		Note the use of ( ) with the pipe symbol to specify the 'or' condition
/[0-9]*/	Matches if there are zero or more numbers in the line
/^[^#]/		Matches if the first character is not a # in the line
Notes:
	1. Regular expressions are case sensitive
	2. Regular expressions are to be used where pattern is specified

Other

Counts
Nearly every command may be preceded by a number that specifies how many times 
it is to be performed. For example, 5dw will delete 5 words and 3fe will move 
the cursor forward to the 3rd occurence of the letter e. Even insertions may be 
repeated conveniently with thismethod, say to insert the same line 100 times.

Markers
Named markers may be set on any line in a file. Any lower case letter may 
be a marker name. Markers may also be used as limits for ranges.
mc	Set marker c on this line
`c	Go to beginning of marker c line.
'c	Go to first non-blank character of marker c line.

Ranges
Ranges may precede most "colon" commands and cause them to be executed on a 
line or lines. For example :3,7d would delete lines 3-7. Ranges are commonly 
combined with the :s command to perform a replacement on several lines.
:.,$s/pattern/string/g 
		^ Range - make a replacement from the current line to the end of the file.
:3,7		Range - Lines 3-7
:.		Range - Current line
:$		Range - Last line
:'c		Range - Marker c
:%		Range - All lines in file
:g/pattern/	Range - All lines that contain pattern

Files
:w file		Write to file
:r file		Read file in after line
:n		Go to next file
:p		Go to previos file
:e file		Edit file
!!program	Replace line with output from program

Status
:.=	Shows current line number
:=	Shows number of lines in file
Control-G	Shows filename, current line number, total lines in file, and % of file location
l	Displays tab (^l) backslash (\) backspace (^H) newline ($) bell (^G) formfeed (^L^) of current line