Impact sockets are designed for use with powered impact wrenches or ‘drivers’, as they are sometimes called. Impact wrenches can be powered pneumatically (by compressed air), electrically, or hydraulically (oil).
The combination of an impact wrench and impact socket can deliver greater torque to the head of a fastener than can be achieved with a manual wrench.
Impact wrenches are often used by mechanics in garages to remove seized nuts and bolts from vehicles, and by racing teams to quickly apply large torque loads to wheel nuts to hold them securely.
An impact wrench stores kinetic energy in a rotating hammer that is forced (impacted) against an anvil which then delivers force to the driver. As this force is delivered on impact in a short burst instead of continually, the torque is multiplied.