Meet Python

Just as learning to drive starts with the steering wheel, accelerator, and brake, learning to code starts with understanding your tools. Python is a powerful yet beginner-friendly programming language — this lesson introduces you to it.

1. What Is Python

Python is a high-level programming language created by Dutch programmer Guido van Rossum and first released in 1991. Its name comes from the British comedy group Monty Python, not the snake.

Python's design philosophy emphasizes code readability — code written in Python is easy to understand, even for non-programmers. Its syntax is clean and expressive; the same feature often requires only one-third to one-fifth the lines of code compared to C++ or Java.

What Can Python Do

Python has an incredibly wide range of applications:

Interpreted vs Compiled Languages

Understanding this helps you grasp how Python works:

• Compiled languages (C, C++, Go): Code is first translated into machine-executable binary by a compiler, then run. Like writing a letter → translating it to English → handing it to the recipient.
• Interpreted languages (Python, JavaScript): Code is translated and executed line-by-line by an interpreter. Like speaking a sentence → a simultaneous interpreter translates it on the spot.

Python is interpreted, which means you can test as you go, making development fast and ideal for beginners to quickly try out ideas.

Python 2 vs Python 3

If you search for Python tutorials online, you might encounter both Python 2 and Python 3:

• Python 2 is the old version, officially discontinued in 2020.
• Python 3 is the current mainstream version. All new projects should use Python 3.

2. Installing Python

On Windows

1. Open your browser and go to https://www.python.org/downloads/
2. Click the yellow "Download Python 3.x.x" button (choose the latest version)
3. Run the installer, make sure to check "Add Python to PATH" at the bottom
4. Click "Install Now" and wait for completion
5. Verify: open Command Prompt (Win + R, type cmd), enter python --version

On macOS

macOS comes with Python 3, but it may not be the latest version. Install via Homebrew:

brew install python

Verify:

python3 --version

On Linux (Ubuntu example)

Most Linux distributions come with Python 3 pre-installed. If not, use the package manager:

sudo apt update
sudo apt install python3

Verify:

python3 --version

3. Running Your First Python Program

Python has two modes: interactive mode and script file mode.

Interactive Mode (REPL)

Interactive mode is like having a conversation with Python — you type a line, and it responds immediately.

Open a terminal and type:

python

You'll see a prompt like:

Python 3.13.0 (main, Oct  7 2025, 10:00:00)
[GCC 12.2.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>>

>>> means Python is waiting for your command. Try typing:

print("Hello, World!")

Press Enter and you'll see:

Hello, World!

Exit interactive mode: type exit() or press Ctrl + Z (Windows) / Ctrl + D (macOS/Linux).

Script File Mode

Writing code in a saved file is the proper way to program:

1. Create a new file named hello.py (.py is the Python extension)
2. Open it with Notepad or VS Code, enter:

print("Hello, World!")

3. Save the file and run it in the terminal:

python hello.py

Output:

Hello, World!

Open terminal → type command → see output. That's the standard workflow.

4. Examples

Example 1: Print a Self-Introduction (Difficulty ⭐)

A simple program that outputs a few lines. Don't worry about understanding everything — just get a feel for it.

# Print a line of text
print("Hello everyone, I'm learning Python!")

# Print multiple lines using \n for line breaks
print("First line\nSecond line\nThird line")

# Print a separator line for readability
print("=" * 20)
print("Welcome to the world of Python!")
print("=" * 20)

Output:

Hello everyone, I'm learning Python!
First line
Second line
Third line
====================
Welcome to the world of Python!
====================

A few new things:

• \n is an escape character that represents a newline, like pressing Enter in Word.
• "=" * 20 repeats the equals sign 20 times, creating a 20-character separator. Python is smart enough to know what multiplying a string by a number means.

Example 2: Python as a Calculator (Difficulty ⭐)

Python can perform various math operations. Open interactive mode and type:

>>> 3 + 5
8
>>> 10 - 4
6
>>> 7 * 8
56
>>> 15 / 4
3.75

If you write a script file calculator.py:

# Simple math with Python
print("3 + 5 =", 3 + 5)
print("10 - 4 =", 10 - 4)
print("7 × 8 =", 7 * 8)
print("15 ÷ 4 =", 15 / 4)

Output:

3 + 5 = 8
10 - 4 = 6
7 × 8 = 56
15 ÷ 4 = 3.75

Example 3: A Simple Interactive Program (Difficulty ⭐⭐)

This program talks to you using input() (to get user input) and print().

# Get user input and greet them

# input() displays a prompt and waits for user input
# The input is stored in the variable 'name'
name = input("Hi, what's your name? ")

# Use an f-string to embed the name in the output
# The f prefix means it's a formatted string; {name} is replaced with the actual input
print(f"Welcome, {name}! Python is fun — let's learn together.")

# Ask for age; input() returns a string, int() converts it to an integer
age = int(input("How old are you? "))

# Do a simple calculation
print(f"In 5 years, you'll be {age + 5} years old — by then you'll be a Python pro!")

Sample run:

Hi, what's your name? Xiao Ming
Welcome, Xiao Ming! Python is fun — let's learn together.
How old are you? 18
In 5 years, you'll be 23 years old — by then you'll be a Python pro!

Common Use Cases

• Automate file processing: Merge thousands of Excel files into one — doing it manually takes a full day, but a few lines of Python can do it in 10 seconds.
• Web scraping: Automatically fetch data from websites — weather forecasts, product prices, news headlines — and save them locally.
• Build web backends: Many popular sites (Instagram, Pinterest, Spotify) use Python for their backend.

❓ FAQ