A box plot is useful for displaying information on :

A box plot displays information on outliers and the median, along with the quartiles.

Correlation involves the relationship between two variables and cannot be shown on a single box plot.

Autocovariance is a time-series measure and lies outside what a box plot depicts.

Options including correlation or autocovariance therefore misstate the box plot's purpose.

The box plot marks the median, the interquartile range and points beyond the whiskers as outliers.

John Tukey introduced the box plot as part of exploratory data analysis.