Introduction to Python

What is Python, and why does everyone seem to be learning it? Python is a programming language: a way of writing instructions that a computer can follow. It's famous for being easy to read, quick to learn and powerful enough to run some of the biggest apps in the world. In this lesson, you'll find out what Python is, what people build with it, and why it's such a great first language.

What is Python?

Python is a high-level, general-purpose programming language. Let's unpack those words:

• Programming language: a set of words and rules for giving instructions to a computer.
• High-level: it's close to human language. Python handles the low-level details, like managing the computer's memory, so you can focus on your idea.
• General-purpose: it isn't limited to one job. The same language can build a website, crunch numbers or control a robot.

Python is also interpreted, which means a program called the Python interpreter reads your code and runs it straight away, without a separate build step. You'll see exactly how that works in How Python Runs Your Code.

Here's a complete Python program. It's just one line:

print("Hello, world!")

Hello, world!

print() is a built-in instruction that shows text on the screen. No setup, no extra lines, no boilerplate (repeated code you must write every time).

Who created Python, and why is it called Python?

Python was created by Dutch programmer Guido van Rossum and first released in 1991. Despite the snake logo, the name comes from the British comedy show Monty Python's Flying Circus. Guido wanted a name that was short, a little playful and easy to remember.

Today, Python is free and open source. Anyone can download it, use it for any project (even commercial ones) and look at how it's built. It runs on Windows, macOS and Linux.

What can you build with Python?

Because Python is general-purpose, it shows up almost everywhere:

• Websites and web apps: frameworks like Django and Flask power the "back end" (the server side) of many sites.
• Data analysis: turning spreadsheets of sales figures or sports statistics into charts and answers.
• Artificial intelligence (AI) and machine learning: most AI research and many chatbots are built with Python tools.
• Automation: small scripts that rename hundreds of files, fill in forms or send reminder emails for you.
• Games and fun projects: simple 2D games, quizzes and programs for tiny computers like the Raspberry Pi.

Who uses Python?

Python isn't just a teaching language. It runs real products used by millions of people every day:

Scientists, bankers, teachers, marketers and hobbyists use Python too. Many people who would never call themselves "programmers" write small Python scripts to save time at work.

Why do beginners love Python?

1. It's readable. Python code looks like simple English, so you can often guess what it does before you've learned it.
2. It needs less code. Tasks that take ten lines elsewhere often take two or three in Python.
3. It gives fast feedback. You type a line, press Enter and see the result instantly.
4. It has a huge community. Millions of people use Python, so answers to almost any question are easy to find.
5. It comes with "batteries included". Python ships with a large standard library (ready-made code for dates, math, files and more), and you can add thousands of free packages.

Look how readable this is. Even without any Python knowledge, you can probably tell what it does:

playlist = ["Morning Run", "Rainy Day Jazz", "Road Trip"]

for song in playlist:
    print("Now playing:", song)

Now playing: Morning Run
Now playing: Rainy Day Jazz
Now playing: Road Trip

How does Python compare to Java and C?

The best way to see Python's simplicity is to write the same tiny program in three languages. Each one prints Hello, world!.

Java:

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, world!");
    }
}

C:

#include <stdio.h>

int main(void) {
    printf("Hello, world!\n");
    return 0;
}

Python:

print("Hello, world!")

Hello, world!

Java and C are excellent languages, but they ask you to learn words like public, static, void and #include before you can say hello. Python lets you start with the idea itself.

Python 2 vs Python 3: which should you learn?

You may see two versions mentioned online. Python 3 was released in 2008 and fixed several design problems in Python 2. Python 2 officially reached its end of life on January 1, 2020, which means it no longer gets fixes, even for security problems.

This tutorial uses Python 3 everywhere. If you find an old tutorial that writes print without parentheses, it's Python 2, and you should skip it.

print(7 / 2)

3.5

A first taste: a coffee order in Python

Here's a slightly bigger program. It stores a few facts about a coffee order and prints a short receipt:

drink = "Cappuccino"
price = 4
cups = 3

print("Order:", cups, "x", drink)
print("Total:", price * cups, "dollars")

Order: 3 x Cappuccino
Total: 12 dollars

Don't worry about every detail yet. You'll learn about names like drink and price in the Python variables lesson. For now, notice how little code it takes to do something useful.

Common beginner mistakes

1. Following a Python 2 tutorial

Old code like this fails in Python 3:

print "Welcome!"

SyntaxError: Missing parentheses in call to 'print'. Did you mean print(...)?

Python 3 always needs parentheses: print("Welcome!").

2. Trying to learn everything at once

Python can do web, data, AI and games, but you don't need all of that on day one. Master the basics in this tutorial first; every specialty builds on them.

3. Reading code without running it

You learn programming by doing. Type every example yourself, run it, then change something and see what happens.

Practice exercise

team = "Lions"
goals = 2

print("Final score")
print(team, "scored", goals + 1, "goals")

Final score
Lions scored 3 goals

What's next?

Now you know what Python is and why it's worth learning. Next, get it running on your own computer: follow our step-by-step guide on how to install Python on Windows, macOS or Linux.