Vertigo is a symptom, rather than a condition itself. It's the sensation that you, or the environment around you, is moving or spinning. This feeling may be barely noticeable, or it may be so severe that you find it difficult to keep your balance and do everyday tasks. Attacks of vertigo can develop suddenly and last for a few seconds, or they may last much longer. If you have severe vertigo, your symptoms may be constant and last for several days, making normal life very difficult.