Installing Python and Running Your First Script

Installing Python and Running Your First Script

Before you install anything, check whether Python is already on your computer. On many machines it is. Installing a second copy you do not need is how beginners end up with two Pythons fighting each other.

Step 1: Check what you already have

Open a terminal. On Windows that is "Command Prompt" or "PowerShell" from the Start menu. On macOS it is "Terminal". On Linux you probably already know. Then type:

python3 --version

On Windows, try py --version and python --version instead. If you see something like Python 3.12.4, you have Python 3 and can continue to Step 3. Any 3.x version from the last few years is fine for this tutorial. If you see Python 2.7, or "command not found", or Windows opens the Microsoft Store, go to Step 2.

Step 2: Install Python 3

Download it only from python.org (Downloads section). Pick the latest stable Python 3 release for your operating system.

On macOS, run the downloaded installer and follow the steps. On Linux, Python 3 is usually already installed; if not, use your distribution's package manager (for example sudo apt install python3 on Ubuntu). Do not try to remove or replace the system Python on Linux or macOS. Other programs depend on it.

Close and reopen the terminal after installing, then repeat Step 1. If the version still does not show, restart the computer before you troubleshoot anything else.

Step 3: Try the interactive shell

Type python3 (or py on Windows) and press Enter. You will see >>>. That is Python waiting for a command. Type this and press Enter:

print("Hello, I can run Python")

It prints the sentence back. To leave, type exit() and press Enter. The shell is good for quick tests. Real programs go in files.

Step 4: Write and run your first script

Create a folder called python-practice. Open a plain text editor. Notepad works, but a code editor like Visual Studio Code is better because it colors the code and shows mistakes. Do not use Word. It adds hidden formatting and "smart quotes" that Python cannot read.

Save this as first.py inside that folder:

name = "Ana"
print("Hello,", name)
print("2 + 3 =", 2 + 3)

In the terminal, go to the folder and run it:

cd python-practice
python3 first.py

On Windows, use py first.py. You should see:

Hello, Ana
2 + 3 = 5

That is a real program. Small, but real.

Troubleshooting, most likely cause first

• "No such file or directory" / "can't open file": you are in the wrong folder. Run cd into the folder that contains first.py, or check the file name. Windows sometimes saves it as first.py.txt.
• "python3 is not recognized" on Windows: use py, or fix PATH as described in the warning above.
• "SyntaxError: invalid character": you probably have curly quotes from a word processor. Retype the quotes in a code editor.
• Nothing happens: check that the file was saved. Unsaved editor changes do not exist as far as Python is concerned.

What happens if you skip this step

You try to learn Python inside some website's online editor, which is fine for a day. Then you try to run something on your own computer, nothing works, and you do not know if the problem is your code or your setup. Getting a clean install working now separates those two problems. After this, if something breaks, it is the code.

Did first.py print both lines? If not, do not move on yet.