In descriptive statistics, a box plot is a convenient way of graphically depicting the five-number summary, which consists of the smallest observation, lower quartile, median, upper quartile and largest observation.

The box plot may also identify outliers and possibly the mean.

A plain-text version might look like this:

                            +-----+-+
  *           o     --------|   + | |----
                            +-----+-+

+---+---+---+---+---+---+---+---+---+---+ 0 1 2 3 4 5 6 7 8 9 10

For this data set (values are approximate, based on the figure):
  • smallest observation (minimum) = .5
  • lower quartile = 7
  • median = 8.5
  • upper quartile = 9
  • largest observation (maximum) = 10
  • mean = 8
  • the value 3.5 is a "mild" outlier
  • the value .5 is an "extreme" outlier
  • the smallest value that is not an outlier is 5
  • the data is skewed to the left (negatively skewed)