pip: installing packages in Python

Python comes with a large standard library, but most real projects use third-party packages too: an HTTP client, a test framework, a data library. pip is the tool that installs them. It downloads packages from the Python Package Index (pypi.org) and puts them where your Python can import them.

Every command here was run with Python 3.13 and pip 26.1, and the usage was checked against the pip user guide.

Use python -m pip

pip is also a command on its own, but the docs recommend running it through the interpreter:

python3 -m pip --version

python3 -m pip uses the pip that belongs to that exact Python, which matters when a machine has more than one. On my machine, the plain pip command isn’t on the PATH at all, while python3 -m pip works.

Use a virtual environment first

A virtual environment is a folder with its own Python packages, so installing into it doesn’t touch other projects. The packaging guide says it is “recommended to use a virtual environment when working with third party packages”:

python3 -m venv .venv
source .venv/bin/activate

On Windows, activate with .venv\Scripts\activate. After activation, python and pip point to the environment.

Install a package

python -m pip install requests
python -c "import requests; print(requests.__version__)"

2.34.2

The import name and the package name can differ. Your version may be newer.

You can pin a version or set a minimum:

python -m pip install "requests==2.34.2"
python -m pip install "requests>=2.30"

See what’s installed

python -m pip list
python -m pip show requests

list prints every package in the environment; show details one package, including what it requires and where it’s installed:

Name: requests
Version: 2.34.2
License: Apache-2.0
Location: .../.venv/lib/python3.13/site-packages
Requires: certifi, charset_normalizer, idna, urllib3
Required-by:

pip list --outdated shows which packages have newer versions.

Save the list: requirements.txt

freeze prints every installed package with its exact version; saved to a file, it lets you rebuild the same environment:

python -m pip freeze > requirements.txt

certifi==2026.7.22
charset-normalizer==3.5.2
idna==3.20
requests==2.34.2
urllib3==2.8.0

To install from the file in a new environment, use -r:

python -m pip install -r requirements.txt

The docs describe a requirements file as “just a list of pip install arguments placed in a file”. freeze lists the dependencies of your dependencies too, which is why certifi and urllib3 appear even though you installed only requests.

Upgrade and uninstall

python -m pip install --upgrade requests
python -m pip uninstall requests

uninstall asks for confirmation; -y skips it.

Common mistakes

• Installing into the wrong Python. If pip install succeeds but import fails, the pip you ran belongs to a different Python.
• Installing into the system Python. On macOS and Linux, the operating system uses it itself.

What’s next

Next in the series: uv, a faster tool that also manages the project and the virtual environment for you.