Why are interquartile range and median called robust statistics?

The IQR and median are called robust statistics because they more resilient to outliers and/or data errors.

For example, the mean and the standard deviation are measures of central tendency and dispersion, respectively, that are most commonly used, but they have the problem that they get (sometimes radically) affected when there are outliers, which is not the case for the median and IQR, which are robust measures of central tendency and dispersion