The Market Volatility Index, commonly known as the VIX, is a financial indicator that measures the expected volatility of the stock market over the next 30 days. It is often referred to as the "fear gauge" because it tends to rise during periods of market uncertainty or economic distress, reflecting investor anxiety. The VIX is calculated using options prices on the S&P 500 index, which represents a broad cross-section of the U.S. stock market. A higher VIX value indicates greater expected volatility, while a lower value suggests a more stable market environment. Investors use the VIX to gauge market sentiment and make informed trading decisions.