Sorting algorithm
![An example of stable sort on playing cards. When the cards are sorted by rank with a stable sort, the two 5s must remain in the same order in the sorted output that they were originally in. When they are sorted with a non-stable sort, the 5s may end up in the opposite order in the sorted output.](/Images/godic/202501/09/Sorting_stability_playing_cards.svg0228.png")
![](/Images/godic/202501/09/Sorting_playing_cards_using_stable_sort.svg0228.png")
![A bubble sort, a sorting algorithm that continuously steps through a list, swapping items until they appear in the correct order.](/Images/godic/202501/09/Bubblesort-edited-color.svg0228.png")
![A Shell sort, different from bubble sort in that it moves elements to numerous swapping positions](/Images/godic/202501/09/Shell_sorting_algorithm_color_bars.svg0228.png")
A sorting algorithm is an algorithm that puts elements of a list in a certain order. The most-used orders are numerical order and lexicographical order. Efficient sorting is important for optimizing the use of other algorithms (such as search and merge algorithms) which require input data to be in sorted lists; it is also often useful for canonicalizing data and for producing human-readable output. More formally, the output must satisfy two conditions: