[simonw]

Virtual environments are, sadly, absolutely crucial for Python beginners to get their heads around if they are to do anything more advanced then "hello world".

When I'm getting someone started I usually say:

"There is a magic incantation involved in Python development called 'activating your virtual environment' - if stuff isn't working as you expect, check that you have done this. Development environments are the hardest thing about learning to program. I'm so sorry."

[BryanBeshore]

pip freeze > requirements.txt

When first learning python and virtual environments, it took me a little bit of time to understand that the virtual environment is basically a clean slate.

The command above saved a lot of time. I’d go so far as to having a set of requirements files ready to go for certain types of projects just to get started.

[coopreme]

Check out pipenv, it really is a lot simpler.