In quick sort algorithm, we pick an element from array of elements called pivot. Then compare the the values from left to right until a greater element is find then swap the values. Again start comparison from right with pivot. When lesser element is find then swap the values. Follow the same steps until all elements which are less than the pivot come before the pivot and all elements greater than the pivot come after it. After this partitioning, the pivot is in its last position. This is called the partition operation.
For more information,please visit the following link:http://roseindia.net/java/beginners/arrayexamples/QuickSort.shtml