Need of Rank in Union

I have seen implementation of rank in disjoint set union find.
Why do we need to use rank while finding union in Kruskal’s ago ?

@chikugoel1998
The explanation is given in the starting

If your doubt is resolved please close it

I hope I’ve cleared your doubt. I ask you to please rate your experience here
Your feedback is very important. It helps us improve our platform and hence provide you
the learning experience you deserve.

On the off chance, you still have some questions or not find the answers satisfactory, you may reopen
the doubt.