title: Why is it termed heap sort is best for external sorting?
body: <p>While studying sorting algorithms, it is referred to as heap sort is used for external sorting.
  I am not able to figure out how does it differ in terms of sorting techniques when we deal with the external storage? Or What is that something which heap sort does uniquely to be considered useful for external sort?</p>
  
  <p>Could someone explain this?</p>