Quicksort is an efficient algorithm for sorting values in a list. A single element, the pivot, is chosen from the list. All the remaining values are partitioned into two sub-lists containing the values smaller than and greater than the pivot element.
Ideally, this process of dividing the array will produce sub-lists of nearly equal length, otherwise, the runtime of the algorithm suffers.
When the dividing step returns sub-lists that have one or less elements, each sub-list is sorted. The sub-lists are recombined, or swaps are made in the original array, to produce a sorted list of values.
Quicksort is a classic sorting algorithm with an excellent average runtime. Understanding the strategy behind quicksort will improve your ability to reason about sorting algorithms.