Cut-and-Paste
It is never necessary to remember line numbers in full-screen mode. Visual allows you to mark, hold, move, copy, replicate, or delete a block of text, all visually. This is called "cut-and-paste" and is done by putting special indicators in the two blank columns at the left of each text line before you press the Enter key. For example, DD indicates a block of text to be deleted.
Dividing and Gluing Operations
Excluding Lines From Visual Mode Display
Justifying Lines in Visual Mode
Marking Changes Without Using Line Numbers