RobustScaler is a data preprocessing technique used in machine learning to standardize features by removing the median and scaling the data according to the interquartile range (IQR). This method is particularly useful for datasets with outliers, as it focuses on the central portion of the data, making it less sensitive to extreme values. By applying RobustScaler, the transformed data will have a median of zero and an IQR of one. This helps improve the performance of various algorithms, especially those that rely on distance calculations, such as k-nearest neighbors and support vector machines.