Python functions are like reusable mini-programs that help you organize and simplify your code. Let’s break it down 🧠🔧

🧱 What Is a Function?

A function is a block of code that performs a specific task. You define it once and call it whenever you need it.

def greet():
    print("Hello there!")

• def starts the function definition.
• greet is the function name.
• The code inside runs when you call greet().

🎯 Why Use Functions?

• Avoid repetition: Write code once, reuse it.
• Improve readability: Break complex tasks into smaller chunks.
• Make debugging easier: Isolate logic into testable units.

🧪 Functions with Parameters

You can pass data into functions using parameters:

def greet(name):
    print(f"Hello, {name}!")

• Call it like greet("Alice") → Output: Hello, Alice!

🔙 Returning Values

Functions can also return results:

def add(a, b):
    return a + b

result = add(3, 5)
print(result)  # Output: 8

🧠 Advanced Features

• Default values: def greet(name="friend")
• Arbitrary arguments: def greet(*names)
• Keyword arguments: def greet(**info)
• Nested functions: Functions inside functions!

🧪 Real-Life Example

def calculate_discount(price, discount):
    return price * (1 - discount)

print(calculate_discount(100, 0.2))  # Output: 80.0