Quartiles are sections of data sets that divide those sets into four even pieces. These sections are divided by the lower, middle, and upper markers located on the points separating the bottom 25%, middle 50%, and top 25% of a data set, respectively. Quartiles on their own are not super useful, but they can be used in other calculations, like finding the interquartile range of a data set, that help understand how clustered a data set is. These equations help find the markers separating the quartiles.