What Is Python, and Installing It
What you’ll learn in this lesson
- What Python is and why it is called a high-level language
- How to download Python from python.org
- How to install it on Windows, Mac, or Linux
- How to open IDLE, the tool that comes with Python
- How to check that your installation works
What Python is
Python is a programming language: a way of writing instructions that looks much like plain English. It is called a high-level language because it sits far above the numbers the computer really runs on — you write words like print and name, and Python handles the translation. A low-level language, by contrast, forces you to manage tiny details yourself. High-level means easier for humans, and that is exactly what a beginner wants.
Python is also interpreted, which means Python reads and runs your code one line at a time, right away. You do not have to wait for a separate “build” step before seeing a result. Type a line, press Enter, see what happens. That instant feedback is a big part of why Python is friendly to learn.
Python 3 is the current version of the language. Older Python 2 is out of date, so everything in this course uses Python 3. When a tutorial just says “Python” with no version number, assume it means Python 3.
Download Python from python.org
Python is free. You download it from its official website, python.org:
- Open your web browser and go to python.org.
- Click Downloads and choose the download for your system (Windows, macOS, or Linux).
- Download the file and run it.
Do not download Python from anywhere else. The official site always has the current, safe version.
Install it on your system
Windows
Python gives Windows users two ways to install it. Option A is the one the Python team recommends, so start there. Use Option B only if Option A doesn’t work on your computer.
Option A: The Python install manager (recommended)
- Go to python.org/downloads, choose the Windows download labeled “Python install manager,” open the file you downloaded, and click Install. Prefer the Microsoft Store? Open the Microsoft Store app, search for Python Install Manager, and click Install. Both versions are identical.
- The install manager does not include Python itself yet. Click Start, type
cmd, and open Command Prompt. - Type
pythonand press Enter. The first time, Windows downloads and installs the latest Python for you, which can take a minute. Say yes if it asks to continue. If it asks about adding a folder to your PATH, that is optional and you can skip it. When you see>>>, Python is ready. Typeexit()and press Enter to leave. - Click Start, type
IDLE, and open it. If IDLE isn’t listed, typepython -m idlelibin Command Prompt instead.
Command Prompt is only needed for this install. Once IDLE shows up in your Start menu, you can open it from there every time.
Option B: The traditional installer (only if Option A doesn’t work)
- Download the Windows installer (the
.exefile) for a current Python 3 release from python.org. - Double-click it. On the very first screen, tick “Add python.exe to PATH” before you click anything else.
- Click Install Now and wait.
- When you see “Setup was successful,” click Close. If it offers “Disable path length limit,” you can click it or skip it. Either is fine for this course.
- Click Start, type
IDLE, and open it.
Mac
Run the downloaded macOS installer and follow the steps. It installs Python and IDLE together. After installing, you can check your work in the Terminal app, but you do not need the Terminal for this course — IDLE is enough.
Linux
Python 3 is usually already installed. If it is not, use your system’s package manager (for example, sudo apt install python3 on Ubuntu). On Ubuntu and Debian, IDLE is a separate package, so if it is missing, install it with sudo apt install idle3.
You do not need to install anything else for this course. No paid software, no extra tools, and no accounts are required. Python and IDLE are everything.
Can’t install Python on your computer?
That’s okay. Many school and work computers don’t allow new programs, and Chromebooks can’t run the Windows installer. You can still learn Python in this course. Use the in-browser Python runner, which runs real Python in your browser with nothing to install. Type the same lines you’d type in IDLE. You can type and run the short lines from Lessons 2–15 in the runner — print, variables, numbers, strings, comparisons, if statements, loops, lists, dictionaries, and functions. Saving practice files needs IDLE, and so does Turtle drawing in Lesson 10, so install Python on your own computer when you can. If you can install later, come back to this lesson and try again.
Open IDLE
IDLE is the small programming tool that comes bundled with Python itself. It has two jobs in this course: it gives you a window where you can type Python lines and see results at once (called the shell), and it lets you write and save program files.
To open it:
- Windows: open the Start menu, type
IDLE, and open the IDLE app for your Python 3 version. - Mac: open Finder, go to Applications, open the Python 3 folder, and open IDLE.
- Linux: open a terminal and type
idle3, then press Enter.
You should see a window titled “IDLE Shell” with a prompt that looks like >>>. That prompt is Python waiting for your first instruction.
Check that it works
In the IDLE shell, type this line and press Enter:
print("Hello, Python!")Output:
Hello, Python!If you see Hello, Python! printed back, your installation works and you are ready. If IDLE does not open or the line gives an error, check two things: that you installed Python 3 (not Python 2), and that you typed the line exactly, quotes and all.
You can also check the version. In the shell, the first lines IDLE prints when it opens include the Python version number. As long as it starts with 3, you are set — the exact number after that does not matter for this course.
If something goes wrong
Click a problem to see the fix.
I can’t find IDLE.
Click Start and type IDLE, not “Python.” If it isn’t there, restart your computer once and try again. Still missing? Open Command Prompt and type python -m idlelib to start IDLE that way. You can also check Settings > Apps for an entry that includes Python.
The first python command seems stuck.
The first time, Windows has to download Python, which can take a minute or more on a slow connection. Wait until you see >>> or a message telling you what to do next.
Typing python in Command Prompt opens the Microsoft Store or says Python was not found.
- Make sure you installed the Python install manager (Option A, step 1).
- Click Start, type Manage app execution aliases, and open it.
- Check that the alias named Python (default) is turned on. If it already is, switch it off and on again.
- Close Command Prompt, open a new one, and try again. If it still fails, restart your computer.
If you used Option B, uninstall Python from Settings > Apps, then install it again and tick “Add python.exe to PATH” on the first screen.
Windows says “Windows protected your PC.”
Click More info, then Run anyway, but only if you downloaded the file from python.org.
The installer asks for an administrator password, or says you don’t have permission.
You’re probably on a work or school computer that blocks installs. Use the in-browser runner described in the “Can’t install Python on your computer?” section on this page.
The installer won’t start, or says it can’t run on your PC.
Current versions of Python need Windows 10 or newer. On an older version of Windows, use the in-browser runner described in the “Can’t install Python on your computer?” section on this page.
IDLE opens, but print("Hello, Python!") gives an error.
The usual cause is the quotes. If you copy the line from a Word document or an email, the quotes can turn curly, like print(“Hello, Python!”). Python only accepts straight quotes, like print("Hello, Python!"). Type the line yourself, or copy it from this page.
I have more than one Python installed.
That’s fine. Any version that starts with 3 works for this course.
Press play on any slide and the lesson plays on by itself from there. You can still click Next or click a slide to move on.
Download the Lesson 2 slides (PowerPoint, with narration)
Download the Lesson 2 slides (PDF)
Hands-on exercise
- Install Python 3 with the install manager (Option A). If you use the traditional installer instead, tick "Add python.exe to PATH" on its first screen.
- Open IDLE and confirm you see the
>>>prompt. - In the shell, print your own name in quotes.
- Print the result of
10 + 5in the shell and check you get15.
Lesson 02: What Is Python, and Installing It
This is the check from the lesson: after installing Python, you type one line in IDLE and Python prints it back.
Try this: Change the name to your own name and press Run again — the greeting changes to greet you.
The code that runs
Output
Press Run to see the output here.
Practice file
Save this as lesson02-practice.py and run it with F5 in IDLE.
# Lesson 2: What Is Python, and Installing It
# WHAT TO DO: This is your first program file. Line 9 is unfinished:
# replace the placeholder words inside the quotes with your own name.
# HINT: Only change the words inside the quotes. Do not touch the
# print part or the quotes themselves.
# Run with F5 in IDLE. You are done when line 2 prints your real name.
print("Hello, Python!")
print("My name is TODO - put your name here") # <-- CHANGE THIS LINE
print(10 + 5)Key takeaways
- Python is a free, high-level, interpreted language that reads much like English.
- Download it only from python.org; Python 3 is the current version.
- On Windows, use the Python install manager; if you use the traditional installer instead, tick "Add python.exe to PATH" on its first screen.
- IDLE comes with Python and is all you need: a shell for trying lines, and an editor for saving programs.
print("Hello, Python!")in the shell is your installation check.
Next lesson: Your First Program.
Quick quiz
- What does "high-level language" mean?
- What does "interpreted" mean for Python?
- What is the official website to download Python from?
- If you install with the traditional installer (Option B), what box must you tick on the first screen, and why?
- What is IDLE, and what are its two jobs in this course?
Answer key: 1. A language that lets you write readable words instead of managing tiny computer details yourself. 2. Python reads and runs your code one line at a time, right away. 3. python.org, the official site. 4. "Add python.exe to PATH" — only if you use the traditional installer (Option B); without it, the computer may not find Python later. 5. The tool bundled with Python; it gives you an interactive shell and lets you write and save program files.