Which is the preferred way to concatenate a string in Python?

Since Python’s string can’t be changed, I was wondering how to concatenate a string more efficiently?

I can write like it:

s += stringfromelsewhere

or like this:

s = []

s.append(somestring)
    
# later
    
s="".join(s)

While writing this question, I found a good article talking about the topic.

http://www.skymind.com/~ocrow/python_string/

But it’s in Python 2.x., so the question would be did something change in Python 3?