Two years ago I wrote a post called What’s in which Python 2.x? which summarized the changes in the Python 2.x releases. Today when I showed it to someone, they asked, “Do you have one for 3.x?”

Here it is. BTW, there is also What’s in which Python 3.4–3.6?.

Update: I’ve now collected all the “What’s in which Python”s onto a single page: What’s in which Python.

Some things to remember about Python 3:

• 3.0 came out about the same time as 2.6, so they share a number of features. 2.7 came out between 3.1 and 3.2, so there’s overlap there as well.
• A language moratorium prevented significant changes in 3.2.

3.0: December 3rd, 2008

• strings are now unicode, no u”” literals
• print as a function
• iterators instead of lists: range, .keys, .items, .values, zip, map, filter
• nonlocal
• function annotations
• lots of things moved in the standard library

Full list of 3.0 changes.

3.1: June 27th, 2009

• OrderedDict and Counter classes
• __main__.py

Full list of 3.1 changes.

3.2: February 20th, 2011

• argparse
• concurrent.futures
• __pycache__ directories
• hasattr doesn’t swallow all exceptions

Full list of 3.2 changes.

3.3: September 29th, 2012

• yield from
• u”” literals are back
• unittest.mock
• hash randomization
• New flexible string representation
• venv module
• more of import implemented in Python

Full list of 3.3 changes.