You can field in the slips, at gully, at square leg or even at silly point. When a position is described as 'deep' or 'long' as in deep mid-wicket or long off then the fielder is usually placed right out on the boundary.
In all forms of cricket, only two fielders are allowed in the quadrant between the fielding positions of square leg and long stop. This is to prevent the outlawed and controversial bodyline tactics from being used. No fielder is allowed on or over the pitch until the batsman has had a chance to play the ball.
