A Steadicam is a mechanical device that is simultaneously a brand (Tiffen Steadicam), a name for a product, and a term used to refer to stabilized handheld filming.
In the early days of filmmaking, if someone wanted a mobile shot, they’d either need to set up a dolly (a leveled and wheeled mount that goes along a predetermined track) or have the camera operator hold and move the camera. The Steadicam was invented to give Hollywood filmmakers a mobile, camera-stabilizing option for smooth, dynamic movement that enabled the Steadicam operator to follow actors or create extended scenes without distracting shaking.