When the neck and head are suddenly forced backward and then forward, the cervical spine (neck) is put through motions that are both fast and stressful. This can result in pain that ranges from minor to debilitating. Some also experience shoulder and back pain, as well as headaches.
Car crashes are the most common cause of whiplash, though sports, accidents, and any high impact activity can be a cause. Intervertebral discs can potentially be damaged, as can fact joints, and other neck structures.