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

Which installer variant should I use? [CHANGED in 3.6.6]

With Python 3.6.5, the python.org website now provides two installer variants for download: one that installs a 64-bit-only Python capable of running on macOS 10.9 (Mavericks) or later; and one that installs a 64-bit/32-bit Intel Python capable of running on macOS 10.6 (Snow Leopard) or later.  (This ReadMe was installed with the $MACOSX_DEPLOYMENT_TARGET variant.)  Previous Python 3.6.x releases only provided the 10.6 or later installer. If you are running on macOS 10.9 or later and if you have no need for compatibility with older systems, use the 10.9 variant.  Use the 10.6 variant if you are running on macOS 10.6 through 10.8, if you need to maintain compatibility with previous 3.6.x releases, or if you want to produce standalone applications that can run on systems from 10.6.  The Pythons installed by these installers are built with private copies of some third-party libraries not included with or newer than those in macOS itself.  The list of these libraries varies by installer variant and is included at the end of the License.rtf file.

CHANGED in 3.6.6:  the 10.9+ 64-bit-only installer variant is now the default download.  The 10.6+ variant is available from the $FULL_VERSION release page.

Certificate verification and OpenSSL

This variant of Python 3.6 now includes its own private copy of OpenSSL 1.0.2.  Unlike previous releases, the deprecated Apple-supplied OpenSSL libraries are no longer used.  This also means that the trust certificates in system and user keychains managed by the Keychain Access application and the security command line utility are no longer used as defaults by the Python ssl module.  A sample command script is included in /Applications/Python 3.6 to install a curated bundle of default root certificates from the third-party certifi package (https://pypi.org/project/certifi/).  If you choose to use certifi, you should consider subscribing to the project's email update service to be notified when the certificate bundle is updated.

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

Using IDLE or other Tk applications [NEW/CHANGED in 3.6.5] 

As of 3.6.5, the 10.9+ installer variant comes with its own private version of Tcl/Tk 8.6. It does not use system-supplied or third-party supplied versions of Tcl/Tk.

CHANGED in 3.6.8: The 10.6+ variant now also uses a private version of Tcl/Tk 8.6.

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.