IQR stands for interquartile range, it is a measure of variability that is used to describe the middle 50% of a data set.Q1 and Q3 are calculated using the formula, where Q1 is the first quartile and Q3 is the third quartile.The IQR is the difference between Q3 and Q1.The IQR is not affected by outliers, making it a robust measure of variability.