Optical image stabilization (OIS)
From The Glossary of Digital Photography
Also called vibration reduction. A technique used to reduce image shake in digital still and video cameras. OIS works by using electromagnets to move a floating lens element in opposition to the movement of the lens. Lenses that have this feature tend to be more expensive than non-OIS lenses. Typically, an OIS system will allow a photographer to handhold an exposure about twice as long (one stop in shutter speed).
