Box Plot

Box Plot is also known as Box and Whisker Diagram. In this graph the beginning of the box represents the 25^th percentile and the end of the box represents the 75^th percentile, the line inside the box marks the meridian or 50^th percentile. The whisker part of this graph can represent a few different values: minimum and maximum, the 10^th and 90^th percentiles, one standard deviation above and below the mean, and any other statistical value of importance relating to the shown data.

The graph shown is a Box (Box and Whisker) Plot of "Guinea Pigs' Tooth growth."  This Box Plot shows the relationship between Tooth Length and Vitamin C dose in mg. The shading of the boxes indicates how the Vitamin C dose was given. Yellow indicates Ascorbic Acid and orange indicates Orange Juice. The horizontal axis shows the Vitamin C dose. The vertical axis shows Tooth Length.

http://sphaerula.com/legacy/R/boxplotTwoWay.html