The Isofix anchors are located on the back seats of the car. These are metal anchors into which the child car seat "clicks" and allow for easy, quick, and safe installation of the seat in the vehicle.
The Top Tether is an additional tether strap on the top or back of the seat, which holds it in place and reduces the forward movement of the seat during a frontal collision, providing extra safety in the event of an accident.