In practice, for MOST developers, the changes between 2 and 3 are minimal. Offhand, print is a function, and there's no distinction between unicode strings and

In practice, for MOST developers, the changes between 2 and 3 are minimal. Offhand, print is a function, and there's no distinction between unicode strings and ascii strings anymore. If you do a lot of "low level" networking involving byte strings, you'll notice the difference, because you can't just jump between bytes and strings anymore. It's this distinction that's delaying a lot of networking related libraries from porting to Python 3 - basically, it's going to be a long, buggy journey. Libraries such as Twisted, have very old codebases - old enough that some of the practices aren't the best, even for Python 2 code. Upgrading it to Python 3 will introduce quite a few breakages. There's a lot more that I can't think of right now, but I'm sure someone else can cover off other differences. There's no reason not to learn both - I use Python 3 for a few personal projects, and Python 2 for work.