Ball joints are crucial components in a vehicle's suspension system, allowing for smooth movement between the control arms and the steering knuckles. They function like a ball-and-socket joint in the human body, enabling the wheels to move up and down while also allowing for steering. These joints are typically made of metal and rubber, providing durability and flexibility. Over time, ball joints can wear out due to constant movement and exposure to road conditions, leading to issues like uneven tire wear or poor handling. Regular maintenance and inspection can help ensure they remain in good condition.