The `DATEADD` function in T-SQL is a powerful tool for manipulating date and time values. It allows you to add specific time intervals, such as days, hours, minutes, seconds, milliseconds, months, or years, to a given date or time. This is essential for tasks like calculating future dates, determining elapsed time, or generating reports based on time-related criteria. For example, you might want to calculate the date three months from now, or determine the date one week before a specific event. `DATEADD` provides the flexibility to perform these calculations. It's a fundamental function for any SQL developer working with temporal data. Understanding `DATEADD` is crucial for tasks involving scheduling, reporting, and tracking durations. The function takes three arguments: the interval to add, the number of intervals to add, and the date or time value to which to add the interval.