Emergency! Who to call: 911 or 112?

I was looking for emergency numbers in Italy. I realized that it its difficult to find all in one place. I have the impression that not everyone knows the number that one should use in case of ANY emergency. I asked some friends, and the answers were different: 111, 118, 911 (?!).

Then I found this enlightening website of the European Emergency Number Association (EENA)

Please, note that the European Emergency Number to dial in ANY case is 112.