Installing Python: A Step-by-Step Guide

Choosing Your Operating System

First, please identify which operating system you are using (Windows or macOS) and follow the specific instructions for it in the sections below. If you are using Linux, you'll find a brief note at the end of the installation section.

Step 1: Checking if Python is Already Installed

Before installing, it's good practice to check if you already have a version of Python. Don't worry if this seems a bit technical; it's a simple check.

You'll need to open your system's command-line tool:

• On Windows: Press the Win key, type cmd or PowerShell, and press Enter.
• On macOS: Press Cmd + Space, type Terminal, and press Enter.

Once the command line is open, type the following command and press Enter:

python --version

You might also need to try this command:

python3 --version

If you see a version number (e.g., Python 3.12.4), then you have Python installed. If it's an older version (e.g., Python 2.x, or a version older than 3.10), I still recommend installing the latest version to follow along with this course. If you get an error message like "command not found," it means Python is not installed or not configured correctly, and you can proceed with the installation steps.

Step 2: Installing Python

We will use the official installer from the Python website, which is the most common and recommended method for developers.

For Windows Users

For a detailed video walkthrough of the installation on Windows, please watch the following video. It is recent and provides clear, step-by-step instructions.

As you follow the video or the steps below, please pay special attention to one crucial step.

Critical Step: Add Python to PATH

During installation, you will see a window like the one below. It is very important that you check the box that says "Add python.exe to PATH". This allows you to run Python from your command line in any directory, which will be essential for our work.

For a detailed text guide that you can refer to, the following article from DigitalOcean is an excellent resource. It covers the same steps and explains the "why" behind them.

For macOS Users

On macOS, the process is also straightforward. Some older versions of macOS came with Python 2 pre-installed, but we will be installing the latest version of Python 3.

This video provides a clear walkthrough for the installation on a Mac.

For a written guide that you can follow along with, the article below from Real Python provides detailed, step-by-step instructions.

After the installation, the installer might open a folder containing some files. You can safely close this window.

For Linux Users

Most Linux distributions come with a version of Python pre-installed. You can install or update to the latest version using your distribution's package manager. For example:

• On Debian/Ubuntu: sudo apt update && sudo apt install python3
• On Fedora: sudo dnf install python3

The Real Python article mentioned above also provides detailed instructions for Linux if you need them.

Step 3: Verifying Your Installation

Once the installation is complete, it's time to confirm that everything is working correctly. This is the same process we performed in Step 1, but this time you should see the new version number you just installed.

1. Open a new command-line window (Command Prompt/PowerShell on Windows, or Terminal on macOS). It's important to open a new one so it recognizes the new installation.

2. Type one of the following commands and press Enter:
   python --version

   or, especially on macOS/Linux:

   python3 --version

You should see the version you just installed, like Python 3.12.4.

A Note on python vs. python3

On some systems, particularly macOS and Linux, python might refer to an older, pre-installed version of Python (like Python 2), while python3 refers to the new version you just installed. For consistency, it's a good habit to use the python3 command if you find that python points to an old version. On Windows, python will almost always refer to the version you just installed.

Conclusion

Congratulations on completing your first lesson! You have successfully installed Python, the primary tool we'll be using to build backend applications. This is a fundamental and essential step for any programmer.

Key Takeaways:

• You learned how to install Python using the official installer for your operating system.
• You understood the critical importance of adding Python to the PATH on Windows to make it accessible from the command line.
• You can now verify your Python installation by opening a command-line tool and running python --version or python3 --version.

Next Up:
In our next lesson, we will set up your development environment by installing Visual Studio Code, a popular and powerful code editor. We will then write and run your very first line of Python code