I was running a Django project, and I had to use a GitHub repo as a third-party dependent in the project by cloning it and incorporating it inside the project. But, for some reason, I couldn’t run the project because of the Module Not Found error which caused by the usage inside third-party folder. So, I had to add that third-party folder to PYTHONPATH variable to run the project.

This is a brief article about what is PYTHONPATH and its intro:

Imagine your computer is like a big library with lots of books, which are like the programs and files on your computer. Now, when you want to run a Python program, it needs to use some special books (libraries or modules) to work correctly.

PYTHONPATH is like a list of favorite aisles in the library where these special books are. When you tell Python, “Hey, I want to run this program,” Python looks at the PYTHONPATH to know where to find the special books (modules) it needs to run your program.


  1. To Find Special Books Easily: Sometimes, you have your own special books (modules) not in the usual aisles. By adding their locations to PYTHONPATH, you tell Python exactly where to find them.
  2. To Share and Use Different Books: If you have many different projects or programs, they might need different special books. You can change PYTHONPATH for each one, so Python knows where to look for the right books for each project.


When you run a Python program, and it needs a special book (module or library), it will start looking in the aisles listed in PYTHONPATH. If it finds the right book there, it will use it! If not, it might tell you it can’t find it or look in the default places it knows.

In summary, PYTHONPATH is used to guide Python on where to find the extra special books (modules and libraries) it needs to run your programs, especially when those books aren’t in the usual places!