The Interquartile Range (IQR) is a statistical measure that represents the range within which the middle 50% of a data set lies. It is calculated by subtracting the first quartile (Q1) from the third quartile (Q3). Q1 is the median of the lower half of the data, while Q3 is the median of the upper half. The IQR helps to identify the spread of the central portion of the data, making it useful for understanding variability. The IQR is particularly valuable in identifying outliers, which are data points that fall significantly outside the typical range. By using the IQR, one can determine thresholds for outliers, typically defined as values that are 1.5 times the IQR above Q3 or below Q1. This method is often used in data analysis and visualization, such as in box plots, to provide insights into the distribution of the data set.