This video describes the workings of a recursive quicksort, which takes a ‘divide and conquer’ approach to the problem of sorting an unordered list. It follows on from previous quicksort videos that covered algorithms for partitioning a list. Line by line, this video examines the execution of a program, written in pseudocode, which makes use of a partitioning function, and also calls itself repeatedly to process successively smaller partitions of the original list until it is fully sorted. Changes to the contents of the call stack are also illustrated as recursive invocations of the quicksort procedure begin and end. I recommend that you review my videos on the call stack and recursion to help you understand what is being described here.