Virtual environments and pip

A virtual environment is a private folder of packages for one project. It stops projects fighting over versions, and nothing gets installed for the whole system. Create one with python -m venv .venv and then activate it: source .venv/bin/activate on macOS and Linux, or .venv\Scripts\activate on Windows.

Then install what you need with pip, such as pip install requests. Record the list with pip freeze > requirements.txt. A stranger then recreates it with pip install -r requirements.txt.

Add .venv to .gitignore. Newer tools such as uv and Poetry wrap the same ideas around a pyproject.toml and a lock file. Either is fine, but learn the plain venv and pip flow first, so you know what they automate.