Dial on nikon lens for what?

There's a dial on some nikon lens that changes somethings from inifite to 0 in foots or meters. What is that dial for? Why some lens have that? What for? It is not the zoom

Added (1). If its the focus ring, then, if is auto focus, like its a AF-S lens, it move itself when auto focusing?

IT's a focus ring, present on all nikon lenses. The distance scale is not on all lenses.