What is the impact of outliers on the skewness of a distribution?

Outliers can have a significant impact on the skewness of a distribution. An outlier can increase skewness if it is further from the mean in the direction of the skew. Conversely, an outlier can decrease skewness if it is further from the mean in the direction opposite to the skew. The extent of the impact depends on the value and direction of the outlier relative to the rest of the data.