Introduction to Python

What 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 almost like writing English sentences rather than complex machine code.

When you write Python, the computer reads your instructions and executes them. You can use Python to build websites, automate tasks, analyze data, create AI systems, write games, and much more — all with the same language.

Why 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.

Compare: Hello World in 3 languages

// 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!" << std::endl;
    return 0;
}

# Python (simple, clean, readable)
print("Hello, World!")

Python lets you do the same thing in 1 line instead of 5–8 lines. This is why beginners learn Python 3× faster than other languages — and why companies love it too (less code = fewer bugs).

Where Python is used in the real world

Companies that rely on Python

A 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.

Installing Python

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

🪟 Windows Installation

🍎 Mac Installation

🐧 Linux Installation

# Update package list
sudo apt update

# Install Python 3
sudo apt install python3 python3-pip

# Verify installation
python3 --version

💻 Setting Up VS Code (Recommended Editor)

A code editor makes writing Python much easier. We recommend Visual Studio Code — it's free, fast, and has amazing Python support.

Your 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.

Method 1 — Run Python Interactively (REPL)

The Python REPL (Read-Evaluate-Print Loop) lets you type code and see results immediately — perfect for testing.

# 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
5

>>> print("My name is Python!")
My name is Python!

Method 2 — Write a Python File (.py)

For real programs, you write code in a file with the .py extension and run it from the terminal. This is how all real Python projects work.

# This is your first Python program!
# Lines starting with # are comments — Python ignores them

print("Hello, World!")
print("Welcome to Python!")
print("I am learning to code on BitWithBite.")

Going Further — Your Name Program

Let's write a slightly more interesting program that asks for your name and greets you personally.

# greeting.py
# An interactive greeting program

print("=============================")
print("   Welcome to Python! 🐍")
print("=============================")

name = input("What is your name? ")
print(f"Hello, {name}! Great to meet you!")
print(f"Welcome to Python, {name}. Let's build something amazing!")

Don't worry if you don't understand every part yet — you'll learn input() in Module 5 and f-strings in Module 3. For now, just focus on running the code and seeing the output. That's the most important thing at this stage.

Python 2 vs Python 3

You might encounter old tutorials or books that use Python 2. Here's what you need to know about the differences:

# Python 2 (OLD — do NOT use)
print "Hello"         # print is a statement
5 / 2  # gives 2       # integer division by default
unicode("hello")      # separate unicode type

# Python 3 (CURRENT — always use this)
print("Hello")         # print is a function
5 / 2  # gives 2.5     # true division by default
"hello"               # all strings are unicode

The rule is simple: always use Python 3. Python 2 reached end-of-life in January 2020 and no longer receives security updates. Every lesson in this course uses Python 3.

The Zen of Python

Python has a philosophy — a set of guiding principles that explain why Python looks and works the way it does. You can read it by running import this in Python. Here are the most important ones for beginners:

Lesson Summary

Let's recap everything you learned in this lesson: