If you want to select some lines of text and search for a word to replace in Vim, many users will do it like this:
vto do the selection.
:to start inputting an editor command.
s/<pat>/<text>/gto search and replace text.
:'<,'>s “applies to whole lines”.1
How about an arbitrary visual selection?
According to a Vim tips found in the footnote, the answer is quite
\%V atom at the beginning of the search pattern.