How long is the New York Stock Exchange Open?

Could you please elaborate on the operational hours of the New York Stock Exchange? I'm curious to know the exact time frame during which trading activities are conducted. Is it a 24-hour market, or does it have specific opening and closing times? If so, what are those times, and are there any exceptions or variations to the standard schedule? Additionally, are there any pre-market or after-market sessions that traders can participate in? Understanding the operational hours is crucial for investors and traders to plan their strategies accordingly.