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 Older Python 2 is out of date, so everything in this course uses Python 3.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.
Python is free. You download it from its official website, python.org:
Do not download Python from anywhere else. The official site always has the current, safe version.
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 A doesn't work on your computer.
Option A: The Python install manager (recommended)
There is no "Add to PATH" box with this method, and you don't need one. It comes with Python 3 and IDLE.
Option B: The traditional installer
Use this if you can't use the Microsoft Store or the install manager.
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). IDLE can be installed the same way if it is missing.
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.
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 11, so install Python on your own computer when you can. If you can install later, come back to this lesson and try again.
I can't find IDLE. Click Start and type IDLE, not "Python." If it isn't there, restart your computer once and try again. Also check Settings > Apps for an entry named Python.
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 above.
The installer won't start, or says it can't run on your PC. The install manager needs Windows 10 or later. On an older version, use the in-browser runner.
Typing python in Command Prompt opens the Microsoft Store or says "Python was not found." You don't need the Command Prompt for this course, so just open IDLE from the Start menu. If you installed with Option B and want to fix it, run the installer again, choose Modify, then Repair, and make sure the PATH box is ticked.
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 email, the quotes may become curly (“ ”), and Python only accepts straight ones (" "). 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.
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:
IDLE, and open the IDLE app
for your Python 3 version.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.
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.
>>> prompt.10 + 5 in the shell and check you get 15.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.
print("Hello, Python!") in the shell is your installation check.Next lesson: Your First Program.
Work through the slides with Helio's narration, or download them:
Open the slidesDownload PowerPointDownload PDF
Run the lesson's example with real Python, right in your browser (Python loads from the internet, so you need to be online).
Download lesson02-practice.pyDownload the solution
# 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)
Save the file as lesson02-practice.py and run it with F5 in IDLE. On a Mac, if F5 does nothing, use Run, then Run Module, from the menu.
Five quick questions on this lesson. Take the Lesson 2 quiz
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