If you are doing development under Windows, you may have to edit Windows’ path.
The task will be illustrated by adding Python’s installation directory to Windows’ path after installing Python to C:\Python27.
VERSION SPECIFIC INFORMATION
Right click on My Computer, then choose Properties.
Windows Vista and 7
Open the file explorer and click on System Properties – Advanced System Configuration. You will be asked for the administrative password.
In Advanced Options, open Environment Variables. In the System Variables section, open “Path” for editing and add ;C:\Python27. Accept as required. Reboot Windows.
Now confirm that Python has been added to Windows’ path: Open a command prompt window and enter python. You should see the Python interpreter with a prompt of >>>. Use Ctrl-Z and enter to exit the interpreter.