Historically MacPython came with a number of useful extension packages
included, because most Macintosh users do not have access to a development
environment and C compiler. For Mac OS X that bundling is no longer done,
but a new mechanism has been made available to allow easy access to
extension packages.
The Python Package Manager helps you installing additional packages
that enhance Python. It determines the exact MacOS version and Python
version you have and uses that information to download a database that
has packages that are tested and tried on that combination. In other
words: if something is in your Package Manager window but does not work
you are free to blame the database maintainer.
PackageManager then checks which of the packages you have installed and
which ones are not. This should also work when you have installed packages
outside of PackageManager. You can select packages and install them,
and PackageManager will work out the requirements and install these too.
Often PackageManager will list a package in two flavors: binary and
source. Binary should always work, source will only work if you have
installed the Apple Developer Tools. PackageManager will warn you about
this, and also about other external dependencies.
PackageManager is available as a separate application and also as a
function of the IDE, through the File->Package Manager menu entry.
