In what situations is Spearman's rank correlation preferred over Pearson's correlation?

Spearman's rank correlation coefficient is a nonparametric measure of rank correlation. It's preferred over Pearson's correlation when the variables are not normally distributed, the relationship is nonlinear, or the data contains outliers. It assesses how well an arbitrary monotonic function could describe the relationship between two variables, without making any assumptions about the frequency distribution of the variables.