Volatility measures the size and speed of price changes in a market. When a market is highly volatile, prices swing sharply in short periods; when volatility is low, prices move slowly and stay more stable. Volatility isn’t good or bad on its own — it simply means more movement, which brings both more opportunity and more risk. Traders pay close attention to volatility because it affects how large a position should be and how much room a trade needs to breathe. Understanding volatility helps a trader prepare instead of being caught off guard.