What is exactly use of "you welcome"?
Suppose there are two scenario:
If someone come to me for help and I did then he might say "thanks". In this scenario I will reply "you welcome".
If I go to shop and buy something and paid bill then shopkeeper said "thanks".
In scenario 2 what do I need to reply him? As I gone there to buy something I can't reply him as "you welcome", right? So, how to reply in that case and what are different ways to reply for thanks as per different scenario?