This package will install Python $FULL_VERSION for Mac OS X $MACOSX_DEPLOYMENT_TARGET for the following architecture(s): $ARCHITECTURES.

Which installer variant should I use?

For the initial alpha releases of Python 3.6, Python.org provides only one installer variant for download: one that installs a 64-bit/32-bit Intel Python capable of running on Mac OS X 10.6 (Snow Leopard) or later.  This will change prior to the beta releases of 3.6.0.  This ReadMe was installed with the $MACOSX_DEPLOYMENT_TARGET variant.  By default, Python will automatically run in 64-bit mode if your system supports it.  Also see Certificate verification and OpenSSL below.  The Pythons installed by this installer is built with private copies of some third-party libraries not included with or newer than those in OS X itself.  The list of these libraries varies by installer variant and is included at the end of the License.rtf file.

Update your version of Tcl/Tk to use IDLE or other Tk applications

To use IDLE or other programs that use the Tkinter graphical user interface toolkit, you need to install a newer third-party version of the Tcl/Tk frameworks.  Visit https://www.python.org/download/mac/tcltk/ for current information about supported and recommended versions of Tcl/Tk for this version of Python and of Mac OS X.  For the initial alpha releases of Python 3.6, the installer is linked with Tcl/Tk 8.5; this will change prior to the beta releases of 3.6.0.

Certificate verification and OpenSSL

Python 3.6 includes a number of network security enhancements that were released in Python 3.4.3 and Python 2.7.10.  PEP 476 changes several standard library modules, like httplib, urllib, and xmlrpclib, to by default verify certificates presented by servers over secure (TLS) connections.  The verification is performed by the OpenSSL libraries that Python is linked to.  Prior to 3.4.3, both python.org installers dynamically linked with Apple-supplied OpenSSL libraries shipped with OS X.  OS X provides a multiple level security framework that stores trust certificates in system and user keychains managed by the Keychain Access application and the security command line utility.

For OS X 10.6+, Apple also provides OpenSSL 0.9.8 libraries.  Apple's 0.9.8 version includes an important additional feature: if a certificate cannot be verified using the manually administered certificates in /System/Library/OpenSSL, the certificates managed by the system security framework In the user and system keychains are also consulted (using Apple private APIs).  For the initial alpha releases of Python 3.6, the 64-bit/32-bit 10.6+ python.org variant continues to be dynamically linked with Apple's OpenSSL 0.9.8 since it was felt that the loss of the system-provided certificates and management tools outweighs the additional security features provided by newer versions of OpenSSL.  This will change prior to the beta releases of 3.6.0 as Apple has deprecated use of the system-supplied OpenSSL libraries.  If you do need features from newer versions of OpenSSL, there are third-party OpenSSL wrapper packages available through PyPI.

The bundled pip included with the Python 3.6 installers has its own default certificate store for verifying download connections.

Other changes

For other changes in this release, see the What's new section in the Documentation Set for this release and its Release Notes link at https://www.python.org/downloads/.

Python 3 and Python 2 Co-existence

Python.org Python $VERSION and 2.7.x versions can both be installed on your system and will not conflict. Command names for Python 3 contain a 3 in them, python3 (or python$VERSION), idle3 (or idle$VERSION), pip3 (or pip$VERSION), etc.  Python 2.7 command names contain a 2 or no digit: python2 (or python2.7 or python), idle2 (or idle2.7 or idle), etc.