0 Basic vi commands

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Insert Text:
a : Insert Text after the cursor
A : Insert text at the end of the current line
I : Insert text at the beginning of the current line
i : Insert text before cursor
o : Open a line below the current line
O : Open a line above the current line
Ctrl-V : Insert any special character in input mode

Delete Text:
D : Delete up to the end of the current line
dd: Delete the current line
dw: Delete from the cursor to the end of the following word
x : Delete the character on which the cursor rests

Change Text:
C : Change up to the end of the current line
cc: Change the current line
cw: Change the word
J : Join the current line with the next one
rx: Replace the character under the cursor with x (x is any character)
~ : Change the character under the cursor to the opposite case

Move Cursor:
$ : Move to the end of the current line
; : Repeat last f or F command
^ : Move to the beginning of the current line
e : Move to the end of the current word
fx: Move cursor to the first occurence of character x on the current
line
Fx: move cursor to the last occurence of character x on the current
line
H : Move cursor to the top of the screen
h : Move one character to the left
j : Move one line down
k : Move one line up
L : Move cursor to the end of the screen
l : move one character to the right
M : Move cursor to the middle of the screen
n|: Move cursor to column n on current line
nG: Place cursor on line n
w : Move to the beginning of the following word

Mark A location:
'x: Move cursor to the beginning of the line that contains mark x
`x: Move cursor to mark x
mx: Mark the current location with letter x

Scroll text:
Ctrl-b : Scroll backward by a full screen
Ctrl-d : Scroll forward by half a screen
Ctrl-f : Scroll forward by a full screen
Ctrl-u : Scroll backward by half a screen

Refresh Screen:
Ctrl-l : Redraw screen

Cut and Paste Text:
"xndd : Delete n lines and move them to buffer x(x is any single
lowercase character)
"Xnyy : Yank n (a number) lines and append them to buffer x
"xnyy : Yank n (a number) lines into buffer x (x is any single
lowercase character)
"xp : Put the yanked lines from buffer x after the current line
P : Put yanked line above the current line
p : Put yanked line below the current line
yy : Yank (copy) current line into an unnamed buffer

Colon Commands:
:!command : Execute shell command
:e filename : Edit file
:f : Display filename and current line number
:N : Move to line n (n is a number)
:q : quit editor
:r filename : Read file and insert after current line
:w filename : Write buffer to file
:wq : Save changes and exit

Search Text:
/string : search forward for string
?string : serach backward for string
n : find next sring

View file Information:
ctrl-g : show filename,size,and current line number

Miscelaaneous:
u : Undo last command
Esc : End input mode and enter visual command mode
U : Undo recent changes to current line

Source: Echo.Or.Id