Hello, World!

Every programming journey starts with the same tiny program: one that prints Hello, World! to the screen. In Python, it takes just one line.

Press Run below to try it. Python runs right in your browser, so there's nothing to install. The first run takes a few seconds while Python loads.

print("Hello, World!")

That's a complete Python program. Here is what each part does:

Python calls commands like print() functions, and you'll meet many more. Running a function is called calling it.

A program can have many lines. Python runs them one at a time, from top to bottom:

print("First")
print("Second")
print("Third")

Tip: You can edit any code on this page. Change the message, then press Run again (or press Ctrl+Enter inside the editor).

Strings

The text inside the quotes is called a string. Python accepts either double quotes or single quotes, as long as they match:

print("I am a string in double quotes")
print('I am a string in single quotes')
print("It's easy to use an apostrophe inside double quotes")

Each print() call writes its output on a new line.

The quotes must match. If you start with ", end with ". To show an apostrophe, wrap the string in double quotes (as above). To show double quotes, wrap it in single quotes:

print('She said "hi" to me')

Quotes also decide what Python does with a value. Without quotes, Python treats 2 + 3 as maths. With quotes, "2 + 3" is just text and is printed exactly as written:

print(2 + 3)
print("2 + 3")

Printing several things at once

You can pass more than one value to print() by separating them with commas. Python puts a space between them for you:

print("Python", "is", "fun")
print("2 + 3 =", 2 + 3)

Notice that 2 + 3 was calculated before printing, but the text "2 + 3 =" was printed as it is. The commas aren't printed; they only separate the values.

Changing the separator and the line ending

print() has two options you can set by writing name=value after the values:

You only add them when you want something different from the default.

Predict first: before you press Run, guess what the three lines will print.

print("2026", "10", "05", sep="-")
print("Loading", end="...")
print("done!")

What happened:

• sep="-" put a - between the values instead of a space, so you get 2026-10-05.
• end="..." ended the line with ... instead of a new line. So the next print carried on in the same line: Loading...done!.

Use sep="" to put nothing at all between the values:

print("Py", "thon", sep="")

Starting a new line inside a string

Writing \n inside a string starts a new line. The backslash tells Python "the next character is special", so \n means "new line" rather than the letter n:

print("Line one\nLine two\nLine three")

\n is called an escape sequence. You'll mostly use these:

print("Name:\tAda")
print("She said \"hi\"")

Comments

Anything after a # on a line is a comment. Python ignores comments. They're notes for the humans reading your code.

# Python skips this line
print("Hi")  # comments can follow code

# print("This line will not run")

Putting # in front of a line is a quick way to switch it off without deleting it. Use comments to explain why the code does something, not to repeat what it obviously does.

Your first error

Mistakes are a normal part of programming, and Python tells you exactly what went wrong. Run this code:

print("Hello")
pritn("World")

Python printed Hello and then stopped with an error message like this:

Traceback (most recent call last):
  File "main.py", line 2, in <module>
    pritn("World")
NameError: name 'pritn' is not defined

Read it from the bottom up:

1. The last line names the problem: a NameError, because Python doesn't know anything called pritn.
2. The lines above show where: line 2, and the code on that line.

Line 1 had already run, which is why Hello was printed. Python stops at the first error, so nothing after it runs. Fix the typo and run it again.

Other common beginner errors:

A SyntaxError means Python couldn't understand the code at all, so nothing runs, not even the lines before the mistake. A NameError happens while the program runs, when Python reaches a name it doesn't know.

Python is case-sensitive: print and Print are different names.

Exercises

Time to practise. Write your code in main.py and press Run.

• When your output is right, you'll see a green Correct! message under the exercise.
• Stuck? Press Hint for a nudge in the right direction. Some exercises have more than one hint.
• Still stuck? Show answer opens one possible solution in answer.py. Try the hints first: you learn the most by working it out yourself.

Exercise 1: Say your name

Print a greeting that includes your name, such as Hello, my name is Ada!.

# Print a greeting with your name

Exercise 2: A three-line banner

Using a single print() call, print this banner.

**********
 Welcome!
**********

# Print the banner with one print() call

Exercise 3: Fix the bugs

This program has three bugs. Fix them so it prints three lines without any errors.

Print("Python is great")
print('I love coding")
print("Let's go!"

Summary

• print() displays values on the screen, and Python runs your lines from top to bottom.
• Strings are text inside matching "double" or 'single' quotes. Without quotes, Python treats things as code or maths.
• Separate several values with commas. sep changes what goes between them (a space by default) and end what goes after them (a new line by default).
• \n starts a new line inside a string, and \t adds a tab.
• # starts a comment, which Python ignores.
• Error messages tell you what went wrong and on which line. Read them from the bottom up.