Installing Python on Windows, macOS and Linux

This lesson is boring and you cannot skip it. Installation is also where a surprising number of people quietly give up, usually because of one of two problems that this lesson will steer you around.

Pick your operating system below and ignore the others.

Windows

Do not install from the Microsoft Store. It works, mostly, until it does not, and the failures are confusing. Use the official installer.

1. Go to python.org/downloads and click the big yellow Download Python 3.x button.
2. Run the downloaded .exe.
3. Tick "Add python.exe to PATH" at the bottom of the first screen. This is the single most important click in this lesson. If you miss it, your terminal will tell you python is not recognised, and the fix is to run the installer again.
4. Click Install Now and wait.

To check it worked, open a new terminal — press Win + R, type powershell, press Enter — and run:

python --version

You should see something like Python 3.12.4. The exact numbers do not matter as long as it starts with 3.12 or higher.

If you get 'python' is not recognized..., the PATH box was not ticked. Run the installer again, choose Modify, and make sure the PATH option is selected.

macOS

macOS ships with an old Python that Apple uses for its own purposes. Leave it alone and install your own alongside it.

The simplest route is the official installer:

1. Go to python.org/downloads, download the macOS installer, and run it.
2. Accept the defaults.

Then open Terminal (Cmd + Space, type "Terminal") and run:

python3 --version

Note the 3. On macOS, python may point at Apple's old version or at nothing at all; python3 is the one you installed. Use python3 everywhere in this course.

If you already use Homebrew, brew install python works just as well.

Linux

Most distributions already have Python 3. Check first:

python3 --version

If it prints 3.12 or newer, you are done. If it is older or missing, install it.

On Ubuntu or Debian:

sudo apt update
sudo apt install python3 python3-pip python3-venv

On Fedora:

sudo dnf install python3 python3-pip

The python3-venv package on Ubuntu matters later, in the module on virtual environments. Installing it now saves a confusing error then.

The two commands you need to remember

Whatever your system, there are two things Python gives you:

• python (Windows) or python3 (macOS and Linux) — runs your code.
• pip or pip3 — installs other people's code.

Check pip is there too:

pip --version

If pip is missing but Python works, try python -m pip --version instead — that form works even when pip itself is not on your PATH, and it is the more reliable way to call it.

Throughout this course, commands are written as python. On macOS and Linux, type python3 instead. It is the same program.

When it does not work

'python' is not recognized on Windows. The PATH box. Re-run the installer and choose Modify. Then close your terminal and open a new one — a terminal reads PATH when it starts and will not notice the change until you restart it.

python opens the Microsoft Store. Windows ships a placeholder that does this when no real Python is installed. Install from python.org, then search "Manage app execution aliases" in Windows settings and switch off the entries for python.exe and python3.exe.

command not found: python on macOS. Use python3. This is normal and not a mistake on your part.

permission denied on Linux. You are missing sudo in front of the install command.

Two versions installed and confusion about which is running. Ask it directly:

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

That prints the full path of the Python that is actually running. When something strange happens later — a package you installed is "not found" — this command is usually how you work out why.

Practice

1. Install Python and confirm python --version (or python3 --version) prints 3.12 or newer.
2. Confirm pip --version works.
3. Run python -c "print(2 + 2)" and check that it prints 4. That is a complete Python program run from the terminal.

If any of the three failed, fix it before moving on. Everything after this assumes a working install, and pushing forward with a broken one wastes hours.

Next: setting up an editor so you are not writing code in Notepad.