splitting vim editor windows horizontally

Press :split to split horizontally the currently edited file into two Vi editor windows.

Press :split file2 to split the Vi editor windows horizontally. The upper Vi editor windows access to file2 while the bottom Vi editor windows access to the currently edited file.

While in splitting mode, press CTRL+WW to switch between split Vi editor window. Copy between files made even easier in split Vi editor windows - just copy the block of lines and press CTRL+WW switching to target file then press p to paste the copied lines.

To close splitted  windows press :q.

 
from  http://bloggerdigest.blogspot.com/2006/09/vi-editor-quick-reference.html