The images allow to easily, visually take in what a sorting algorithm did over time, as it took the list from an unsorted, random state to a completely sorted state. On the horizontal axis, we have a list of numbers, represented as a single line of colors. On the vertical axis, there is time. From the top of the image to the bottom of the image, there is the list of numbers (the line of colored pixels) from a random ordering to a “sorted” rainbow line, by applying each kind of sorting algorithm one step per row.