Day 3/100: First Python Program — Hello, World! + input()

Welcome back to Day 3 of the 100 Days of Python series!
Yesterday, we installed Python and set up our coding environment. Today, we’re writing our first real Python programs using print() and input() — two essential building blocks for any interactive script.

Let’s get started. 🚀

📦 What You'll Learn Today

• How to write and run your first Python program
• The print() function
• The input() function
• How to write comments
• A simple interactive example

🧪 Step 1: Your First Program

Create a new file called hello.py, and type this:

print("Hello, world!")

Now run it:

python hello.py

You should see:

Hello, world!

Congrats — you just wrote and ran your first Python program! 🎉

🧠 What Just Happened?

print() is a built-in Python function. It displays whatever you put inside the parentheses to the screen.

print("Learning Python is fun!")

Output:

Learning Python is fun!

You can also print numbers:

print(2025)
print(5 + 10)

🎤 Step 2: Taking User Input

Let’s make it interactive!

name = input("What's your name? ")
print("Nice to meet you,", name)

Sample Output:

What's your name? Rahul
Nice to meet you, Rahul

Here’s what’s happening:

• input() waits for the user to type something
• Whatever they type gets stored in the variable name
• Then print() shows a message using that value

💬 Pro Tip: Comments

Comments are lines Python ignores. They help you and others understand what your code does.

# This prints a greeting message
print("Hello there!")  # inline comment

Use comments to explain tricky logic or make your code more readable.

🧪 Bonus: Combine Input + Logic

Try this fun challenge:

age = input("How old are you? ")
print("Wow, you're", age, "years old!")

Or:

city = input("Which city are you from? ")
print("Cool! I’ve heard", city, "is beautiful.")

🚀 Recap

Today you learned:

• How to use print() to show output
• How to use input() to collect user input
• How to store and use variables
• How to write comments for clarity