What I don't understand is that python2 and python3 are still advertised as the same language. For Python's developers, this is arguably the case - basing on Python2 source code, they made some changes and just published a new version which they called 3.<p>For some short-lived buzzword tech start-up, this does not matter - with overwhelming likelihood, start-ups from 2008, when python3 was released, will be bust by now. Also, most web code which was written in 2008 will be rewritten by now.<p>For the big internet companies, this also does not matter: They have the manpower to just rewrite their code. Likely, the second version is even a bit better.<p>On the other hand, for research institutions and companies which use complex, long-running enterprise applications - that type of companies that run COBOL, too - the situation is entirely different. A python program for Python2 will not run on Python3. A Python3 program will not run on Python2. The code needs to be rewritten and tested again, and in many cases the people who wrote it originally, and all their implicit knowledge of their domain, are not around any more. Perhaps most affected are scientific organizations which use a lot of code in long-running projects. For these users, Python2 and Python3 are, for all intents and purposes, different languages.