Installing Python

Introduction

Install Python 3.11+ from python.org, or via pyenv (recommended for multi-version) or your OS package manager. Pair it with a virtual environment tool from day one.

Understanding the topic

Core concepts to understand:

• Use pyenv to manage multiple Python versions.
• python -m venv .venv creates an isolated env.
• Activate per shell: source .venv/bin/activate.
• Verify: python --version.

Syntax reference

Visual flow / code:

# macOS / Linux
brew install pyenv
pyenv install 3.12.0
pyenv global 3.12.0

# Create project venv
python -m venv .venv
source .venv/bin/activate
pip install --upgrade pip

Execution workflow

Real-world use

Every serious Python project ships with its own venv (or Poetry/uv). Never install packages globally on a dev machine — you'll regret it.

Best practices

• Always work inside a venv.
• Pin Python version with .python-version.
• Use uv or poetry for modern projects.

Common mistakes

• Mixing system Python with project deps causes breakage.

Hands-on exercise

Interview preparation — practice these questions:

• Why use a virtual environment?
• Pyenv vs conda vs venv?
• How do you pin Python version?

Summary

In summary: Install 3.11+. One venv per project — no exceptions.