Editing
i - insert
a - append
Navigating
j - move down
k - move up
l - move right
h - move left
Exiting
:qa - Close all files
:qa! - Close all files and abandon changes
:w - Save
:wq - Save and close file
:x - Save and close file
:q - Close file
:q! - Close file and abandon changes
ZZ - Save and quit
ZQ - Quit without checking changes