some of my lenses have that
feature…Nikon calls it VR (Vibration Reduction) basically it's for
"anti-shake" when shooting a pic.
basically think of it as helping out with camera shake when you are using a slow shutter speed or having
to hold onto a long telephoto lens.
it doesn't stop motion blur (when the object is moving) as some people think.
I turn it off most times (personal preference)…unless I really need it…it can use up some battery power.