Whiplash, though it is pretty much what is happening in your neck when it occurs, is known medically as "cervical acceleration-deceleration". It happens most often in car accidents when a car is hit from behind or "rear-ended".
The problem with whiplash is that often it isn't noted at the time of the accident because often times the recipient doesn't feel the pain associated with it right away. This can lead insurance companies to discount any later claims to what can potentially turn into a life long grievance if not treated properly.
The sudden movement caused from being hit from behind in a car is much more sudden and traumatic than most people may realize and the damage occurs as quickly as if someone had cracked a whip. This is the sudden motion your neck and head often make, causing your neck muscles and ligaments to push beyond their normal range of motion.
With treatment, recovery can come within a few weeks. But if left untreated, whiplash can produce chronic pain that may last a lifetime.
Among issues that may arise is joint dysfunction. This can cause the joints in the spine or limbs to lose their normal resiliency and powers of shock absorption, which can lead to severely restricted range of motion and be a source of pain.
It can also cause disc herniation, which is injury to the discs between the vertebrae. This causes small tears which will make the inner core of the disc extrude through its outer core. Herniated discs cause symptoms such as shooting pain as well as numbness, tingling and muscle weakness.
It is imperative to get a full exam after an accident so as to rule out any chance of whiplash.