Python Virtual Environments: Setup and Usage Guide

Python Virtual Environments: venv, Activation, pip, and requirements.txt

Quick Answer

A virtual environment is a private Python environment for one project.

Use one .venv per project.

Windows:

py -m venv .venv
.\.venv\Scripts\Activate.ps1

macOS:

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

Last verified: June 9, 2026.

Official Links

• Python venv docs: https://docs.python.org/3/library/venv.html
• Python tutorial on virtual environments: https://docs.python.org/3/tutorial/venv.html
• Python packaging guide: https://packaging.python.org/en/latest/guides/installing-using-pip-and-virtual-environments/
• pip docs: https://pip.pypa.io/en/stable/

What You Will Learn

By the end, you should be able to:

• explain why virtual environments matter
• create a .venv folder
• activate and deactivate environments on Windows and macOS
• install packages inside the environment
• create requirements.txt
• recreate an environment from scratch
• know what should and should not go into Git

1. Why Virtual Environments Exist

Different projects need different packages.

Example:

project-a needs pandas 2.3
project-b needs pandas 2.0

If both projects use one global Python, packages can conflict.

With virtual environments:

project-a/.venv has project-a packages
project-b/.venv has project-b packages

The environment is disposable. Your code is important. .venv can always be deleted and recreated.

2. Create A Project Folder

Windows PowerShell:

mkdir python-venv-practice
cd python-venv-practice

macOS:

mkdir python-venv-practice
cd python-venv-practice

3. Create The Virtual Environment

Windows:

py -m venv .venv

macOS:

python3 -m venv .venv

Linux:

python3 -m venv .venv

.venv is the common folder name. Do not put your source code inside .venv.

4. Activate The Virtual Environment

After activation, your prompt often begins with:

(.venv)

5. Verify The Environment

After activation, run:

python -c "import sys; print(sys.executable)"
python -m pip --version

Expected result:

• the Python path includes .venv
• pip also points inside .venv

On Windows, the path may include:

.venv\Scripts\python.exe

On macOS, the path may include:

.venv/bin/python

6. Install Packages Inside The Environment

After activation:

python -m pip install pandas matplotlib

Test:

python -c "import pandas as pd; print(pd.__version__)"

The packages are installed into .venv, not into your global Python.

7. Deactivate

To leave the environment:

deactivate

This removes .venv from the active terminal PATH.

8. Create requirements.txt

After installing packages:

python -m pip freeze > requirements.txt

Example:

pandas==2.3.0
matplotlib==3.10.0

Commit requirements.txt to Git.

9. Recreate The Environment

If .venv is deleted or someone else downloads your project, recreate it.

Windows:

py -m venv .venv
.\.venv\Scripts\Activate.ps1
python -m pip install -r requirements.txt

macOS:

python3 -m venv .venv
source .venv/bin/activate
python -m pip install -r requirements.txt

10. What Goes Into Git?

Commit:

your_code.py
requirements.txt
README.md
data/sample.csv

Do not commit:

.venv/
__pycache__/
.env

Beginner .gitignore:

.venv/
__pycache__/
*.pyc
.env

11. PowerShell Activation Error

If PowerShell says scripts are disabled, run:

Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

Then close and reopen PowerShell.

Activate again:

.\.venv\Scripts\Activate.ps1

This changes policy only for your current Windows user.

12. macOS PATH Or Activation Problems

If activation fails, confirm the folder exists:

ls .venv/bin

If python3 -m venv .venv fails, check Python:

python3 --version
which python3

If the terminal cannot find newly installed tools, restart Terminal or reload zsh config:

source ~/.zshrc

13. Should You Use venv Or uv?

Use venv when:

• you are learning Python fundamentals
• a course asks for plain Python tooling
• you want to understand environments clearly

Use uv when:

• you want faster project setup
• you want lockfiles
• you want one tool for Python versions, environments, and packages

uv is covered in the next post.

import pandas as pd

scores = pd.DataFrame({
    "name": ["Asha", "Ben", "Chen"],
    "score": [88, 91, 79],
})

print(scores)
print("Average:", scores["score"].mean())

FAQ

Should I create .venv inside every project?

Yes. It keeps project dependencies separate and easy to recreate.

Should I commit .venv to Git?

No. Commit requirements.txt or pyproject.toml, then recreate .venv later.

Do I need to activate the environment every time?

For terminal work, yes. IDEs can also select the .venv interpreter directly.

Can I move a .venv folder to another computer?

Do not rely on that. Recreate it from requirements.txt.

Final Checklist

Windows:

py -m venv .venv
.\.venv\Scripts\Activate.ps1
python -c "import sys; print(sys.executable)"
python -m pip install requests
python -m pip freeze > requirements.txt
deactivate

macOS:

python3 -m venv .venv
source .venv/bin/activate
python -c "import sys; print(sys.executable)"
python -m pip install requests
python -m pip freeze > requirements.txt
deactivate

If the Python path includes .venv, the setup is correct.

Next in this series: Getting Started with uv for Python: Installation and Project Setup →