How do we understand the Iterator for a set

So I have declared a set which will hold a pair of integers. What is temp ? Does it mean that temp will point to a pair<int,int> ?

set<pair<int, int>> myset;
pair<int, int> temp = *(myset.begin());

How is the code below different from the code above? Can I please have a definition of what exactly these codes are doing.

pair<int, int>::iterator temp;
temp = *(myset.begin());