quicksort: selecting pivot

when implementing quicksort, things have select pivot. nonetheless i feeling during pseudocode below, pristine i should select pivot. initial component list? something else?

 duty quicksort(array)
     var list less, greater
     length(array)  1  
         relapse array  
     name mislay focus value focus array
     any x array
         x  focus following insert x less
         else insert x greater
     relapse concatenate(quicksort(less), pivot, quicksort(greater))

can someone assistance me grasp visualisation selecting focus presumably opposite scenarios opposite strategies.