The Python programming language is currently in the midst of a long-term transition from version 2 to version 3. New programmers typically have many questions about which version they should learn. It's confusing to hear that Python 3, which was originally released in 2008, is still not the default installation on many operating systems.
Here's the good news: you can't go wrong starting with either version. While there are differences in unicode and syntax, for the most part if you start with Python 2 and then learn Python 3 you won't be starting from scratch. Likewise, you'll be able to read and write Python 2 code if you started with Python 3.
My personal recommendation for new programmers as of right now is to start with Python 3. There are enough great resources out there that teach version 3 from the ground up.
However, if you are interested in DevOps-type work with configuration management tools such as Ansible or Fabric, then you'll have to stick to Python 2 because they have yet to upgrade to support Python 3. If you know there are libraries you must use in a project, check the Python Walls of Superpowers. If you're using Django, there is also a wall specifically for Python 3 compatibility of popular Django packages.
Wnat to know all of the advantages and what's changed in Python 3 compared to Python 2? There's an official guide to Python 3 changes you'll want to read.
The official porting code to Python 3 page links to resources on porting Python code as well as underlying C implementations. There is also a quick reference for writting code with Python 2 and 3 compatibility.
Porting to Python 3 is like eating your vegetables explains that there are treats in Python 3 that are worth porting for and has some tips on making the transition easier.
Moving from Python 2 to Python 3 is a PDF cheatsheet for porting your Python code.
Django and Python 3 How to Setup pyenv for Multiple Pythons is a screencast showing how to run both Python 2 and 3 for different projects using pyenv.
Scrapy on the road to Python 3 support explains from the perspective of a widely used Python project what their plan is for supporting Python 3 and why it has taken so long to make it happen.
Searching for a complete, step-by-step deployment walkthrough? Learn more about The Full Stack Python Guide to Deployments book.
