Secrets of std::map

I should admit that I'm very poor in C++ Programming. Today, me and one of colleague was trying to understand a code writter by one of a pioneer in our team. We initially thought he wrote a crabby code but indeed we were wrong and he proved his expertness :)

Below is the snippet of similar case.

#include "stdafx.h"
#include < iostream >
#include < map >

int main()
{
 // 1. define the map
 typedef std::map Map;

 // 2. Create the object for it
 Map myMap;

 for (int i=0; i<10; ++i)
 {
    /**************************** 
      3. Whats going on here ???. 
         We just created the object.
         Could this be a buggy code ?? 

         Nope. When we reference an item in map 
         and if the item is not available, 
         it creates the object. Great :)

         I personally seen/used the creation
         of map on the left side,
         something like myMap[2] = 20
         But the below is of something which
         I am seeing new today :)
     **********************************************/
  
             int &ref = myMap[i];
             ref = i;
  
 }
 for (int i=0; i<10; ++i)
 {
             std::cout << myMap[i] << " ";
 }
 std::cout << std::endl;
 
 return 0;
}

Happy Hacking :)