A scissor jack is a mechanical device used to lift heavy objects, commonly found in automotive applications. It consists of two crossed arms that resemble scissors, which expand and contract to raise or lower the load. When the handle is turned, the arms move apart, elevating the platform at the top. Scissor jacks are typically made of metal for strength and durability. They are often included in vehicles as part of the emergency toolkit for changing tires. Their compact design allows for easy storage in the trunk, making them convenient for roadside assistance.