Kendall's Tau is a statistical measure used to assess the strength and direction of association between two ranked variables. It evaluates how well the relationship between the variables can be described using a monotonic function. The value of Kendall's Tau ranges from -1 to +1, where +1 indicates a perfect positive correlation, -1 indicates a perfect negative correlation, and 0 suggests no correlation. This measure is particularly useful in situations where the data does not meet the assumptions of parametric tests, such as normality. Kendall's Tau is often preferred over other correlation coefficients, like Pearson's correlation, when dealing with ordinal data or non-linear relationships.