How to interpret the box and whisker charts?

In a box and whisker plot, the left and right sides of the box are the lower and upper quartiles. For the lower quartile 25% of the data is below this. For the upper quartile 75% of the data is above this. The box covers the interquartile interval, where 50% of the data is found. The line that splits the box in two is the median. The minimum and maximum number of appointments are also displayed with an X diagrammatically. When the X is above or below the whisker, these are classed as outliers.