Why do I have to do it like: print ('Hello') and not: print "hello"??

Answer 1

cause in python3 parenthesis are must

Answer 2

You are calling a function called print, so you need to show what you are passing as the parameters with the parenthesis.

Answer 3

That is actually one of the biggest differences between python 2 and python 3. Or, at least, the one people encounter most often :)

In python 2, "print" was a statement. In python 3, it is a function. And a function is always called by using parentheses.

https://docs.python.org/3/whatsnew/3.0.html