Python · Quick Reference

Lesson 1 — Introduction to Python Cheat Sheet

Python

In one line: Python is a high-level, general-purpose programming language — which basically means it's a language you can use to tell a computer what to do, but in a way that feels almost li...

Key Ideas

1What is Python?. Python is a high-level, general-purpose programming language — which basically means it's a language you can use to tell a computer what to do, but in a way that feels...

2Why Learn Python?. There are hundreds of programming languages. Python has become the most popular one for very specific reasons — it's designed to be human-readable and versatile.

3A Brief History of Python. Python didn't appear out of nowhere. Understanding its history helps you appreciate why it's designed the way it is.

4Installing Python. Before writing code, you need Python installed on your computer. It takes about 5 minutes. Follow the steps for your operating system.

5Your First Python Program. It's time to write actual code. Let's start with the most famous program in the world — "Hello, World!" — and then go a few steps further.

Code Examples

// Java (verbose, lots of boilerplate)
public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

// C++ (complex syntax)
#include <iostream>
int main() {
    std::cout << "Hello, World...

# Update package list
sudo apt update

# Install Python 3
sudo apt install python3 python3-pip

# Verify installation
python3 --version

# Open terminal and type:
python   # Windows
python3  # Mac / Linux

# You'll see something like:
Python 3.12.0 (main, Oct 3 2023)
>>> # This is the REPL prompt. Type code here!

>>> print("Hello, World!")
Hello, World!

>>> 2 + 3...