Market hours refer to the specific times during which financial markets, such as stock exchanges, are open for trading. For example, the New York Stock Exchange operates from 9:30 AM to 4:00 PM Eastern Time on weekdays, excluding holidays. During these hours, investors can buy and sell securities, allowing for price discovery and liquidity. Outside of regular market hours, some exchanges offer pre-market and after-hours trading sessions. These sessions allow traders to react to news and events that occur outside standard hours, but they often come with lower trading volumes and higher volatility. Understanding market hours is essential for effective trading strategies.