Introduction to Python

What is Python?

Python is a high-level, interpreted programming language created by Guido van Rossum and first released in 1991. It’s known for its clean syntax and readability, making it an excellent choice for beginners.

Why Learn Python?

Python is one of the most popular programming languages in the world. Here’s why:

Python’s Key Features

Setting Up Your Environment

Let’s get Python installed on your computer.

Step 1: Download Python

1. Go to python.org
2. Click the “Download Python” button
3. The website will detect your operating system automatically

Step 2: Verify Installation

Open your terminal (Command Prompt on Windows, Terminal on macOS/Linux) and type:

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python --version

You should see something like:

Python 3.12.0

Your First Python Program

Let’s write the classic “Hello, World!” program.

Using the Interactive Shell (REPL)

The REPL (Read-Eval-Print Loop) lets you run Python code interactively:

1. Open your terminal
2. Type python (or python3) and press Enter
3. You’ll see the Python prompt >>>

Now type:

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print("Hello, World!")

Press Enter, and you’ll see:

Hello, World!

Congratulations! You’ve just run your first Python code!

Creating a Python File

For longer programs, we write code in files with the .py extension.

1. Create a new file called hello.py
2. Add this code:

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# My first Python program
print("Hello, World!")
print("Welcome to Python in 30 Days!")

3. Run it from the terminal:

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python hello.py

Understanding the Code

Let’s break down what we wrote:

• print() is a function - it performs an action (displaying text)
• Text inside quotes is called a string
• Lines starting with # are comments - notes for humans that Python ignores

The Python REPL

The REPL is perfect for experimenting with Python:

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>>> 2 + 2
4
>>> "Hello" + " " + "World"
'Hello World'
>>> len("Python")
6

Useful REPL Commands

Choosing a Code Editor

While you can write Python in any text editor, these make coding easier:

1. VS Code (Recommended) - Free, powerful, lots of extensions
2. PyCharm - Professional Python IDE
3. Sublime Text - Fast and lightweight
4. IDLE - Comes with Python, good for beginners

Summary

Today you learned:

• Python is a versatile, beginner-friendly language
• How to install Python on your computer
• How to write and run Python code
• How to use the Python REPL

Next Steps

Tomorrow, we’ll dive into variables and data types - the building blocks of any Python program.

Now, complete the quiz below to test your knowledge and unlock Day 2!