Modern wingers mate. These occasionally drop back to help the full backs, more often though they go forward, sometimes even pop up in the centre forward position. They sometimes work with the full back (and swap roles) temporarily allowing the full backs to put a cross in. They are the ones who often cross the ball in the box for the Jim Fryatt's of this World.
Oh sorry, that assumes that we do play with a centre forward, or is that old school
All this confusion with basic roles for players are down to all these kids games on X-Box and Nintendo's etc