i - insert before the cursor
    I - insert at the beginning of the line
    
    a - insert (append) after the cursor
    A - insert (append) at the end of the line
    
    o - append (open) a new line below the current line
    O - append (open) a new line above the current line
    
    ea - insert (append) at the end of the word
    
    Ctrl + h - delete the character before the cursor during insert mode
    Ctrl + w - delete word before the cursor during insert mode
    
    Ctrl + j - begin new line during insert mode
    
    Ctrl + t - indent (move right) line one shiftwidth during insert mode
    Ctrl + d - de-indent (move left) line one shiftwidth during insert mode
    
    Ctrl + n - insert (auto-complete) next match before the cursor during insert mode
    Ctrl + p - insert (auto-complete) previous match before the cursor during insert mode
    
    Ctrl + rx - insert the contents of register x
    
    Esc - exit insert mode