Don't use Python 3… yet.

Don't use Python 3… yet.
Python 2, Python 3, what's the difference?

Python 3 is the next version of Python. It breaks backwards compatibility with the 2.x branch of Python to give us some great features. Some of which are:

* Unicode strings all around
* Cleaned up standard modules

Why shouldn't I use it, yet?

In the previous paragraph it was noted that Python 3 breaks backwards compatibility with the 2.x branch of Python. The 2.x branch is still the status-quo on all linux, bsd and mac os x distributions.

Because Python 3.x breaks backwards compatibility, a lot of third party modules (those not included in the standard library) are not yet Python 3 compatible. Also, most tutorials and examples you find on the internet are written for Python 2.

If you need to pick a Python version to start developing new applications on, you should pick 2.6. If you are doing work on current applications, pick 2.5.

The 2.x branch of Python is still actively developed.
Python 2.6

Python 2.6 (when ran with the -3 flag) will give warnings about things you do which are deprecated in Python 3 and are not trivially fixed by running the '2to3' tools. If you don't get any warnings running your applications and modules on Python 2.6 it is safe to assume that they will work on Python 3 after you run the '2to3' tools on them.
From http://python-commandments.org/python3.html