The path is where Python searches the modules to Import.
The current path is automatically included.
On Windows add the script dir:
What is my path
>>> import sys >>> from pprint import pprint as pp >>> pp(sys.path) ['', 'C:\\Python33\\python33.zip', 'C:\\Python33\\DLLs', 'C:\\Python33\\lib', 'C:\\Python33', 'C:\\Python33\\lib\\site-packages']
PYTHONPATH is an environment variable, that governs the sequence of directories in which Python searches for module..
A list of strings that specifies the search path for modules. Initialized from the environment variable PYTHONPATH, plus an installation-dependent default.
As initialized upon program startup, the first item of this list, path, is the directory containing the script that was used to invoke the Python interpreter. If the script directory is not available (e.g. if the interpreter is invoked interactively or if the script is read from standard input), path is the empty string, which directs Python to search modules in the current directory first. Notice that the script directory is inserted before the entries inserted as a result of PYTHONPATH.
A program is free to modify this list for its own purposes.
import sys sys.path.append('/ufs/guido/lib/python')