Vertigo is a form of dizziness where the patient has the sensation of moving (often, the sensation that the room is spinning around them) even though they are motionless. It is always caused by a dysfunction of the coordination of the eyes and the structures of the inner ear that both track motion. It usually presents together with nausea and vomiting as well as difficulties standing or walking.
Most vertigo is the result of a benign temporary condition called benign paroxysmal positional disorder, which is no more than the crystals in the inner ear becoming misaligned. This will often resolve itself without treatment. Other causes are motion sickness, Meniere's disease and migraine headaches. However, it can also be induced by alcohol, or merely by spinning in place and stopping. It may also be caused by the common cold, influenza or another infection inflaming the tissues of the inner ear.
In rare cases, vertigo can be a symptom of a problem with the balance centers of the brain. However, in most of those cases, vertigo appears in conjunction with other conditions such as slurred speech, double vision or nystagmus.
The Alfred Hitchcock film Vertigo is named after this symptom (the protagonist of the film gets vertigo because of his fear of heights) and is James Wilson's favourite film. A poster for it appears in his office, he and House watch it at the end of one episode, and when House puts posters from Wilson's porn film in his office, he instructs one of the nurses to get that poster back. Ironically, the protagonist in Vertigo actually suffers from acrophobia.