Dizziness apparently means different things to different people. Some people describe it as the sensation of lightheadedness; others say it means feeling off-balance; still others feel that they or their surroundings are spinning wildly. Whichever definition you prefer, it's caused by a disruption of any one of the systems that control balance in the body. Balance depends on a complex interaction between the brain and the impulses it receives from the nervous system. Any interference with this system can result in the condition described as dizziness. Since the body's sense of balance is determined by the semicircular canals in the ear, this is the source of about half of all dizziness. Still, there could be many other causes. Look for other symptoms that accompany the dizziness, such as headache or nausea, then discuss the matter with your doctor or a specialist in ear, nose and throat conditions.