It’s common to have multiple Python applications running on your system.

When applications require the same module, at some point you will reach a tricky situation where an app needs a version of a module, and another app a different version of that same module.

To solve this, you use virtual environments.

We’ll use venv. Other tools work similarly, like pipenv.

Create a virtual environment using

python -m venv .venv

in the folder where you want to start the project, or where you already have an existing project.

Then run

source .venv/bin/activate

Use source .venv/bin/activate.fish on the Fish shell

Executing the program will activate the Python virtual environment. Depending on your configuration you might also see your terminal prompt change.

Mine changed from

➜ folder

to

(.venv) ➜ folder

Now running pip will use this virtual environment instead of the global environment.

Lessons in this unit:

0:	Introduction
1:	Modules
2:	The Standard Library
3:	Installing packages with pip
4:	▶︎ Virtual environments
5:	Variables scope
6:	Decorators
7:	Docstrings
8:	Introspection
9:	Annotations