Python 2 is an old version of the language that is incompatible with the 3.x line of releases. The language is mostly the same, but many details, especially how built-in objects like dictionaries and strings work, have changed considerably, and a lot of deprecated features have finally been removed in the 3.x line. Note that documentation for Python 2 is provided in the python2-docs package. This package provides the python2 executable; most of the actual implementation is within the python2-libs package.