A functions is a named block of code that does something when you call it. Think of it like mini-program inside your main program.

Why use functioning?

  • To avoid repeating the same code
  • To organize your code better
  • To make your code reusable.

Example 1: A simple function 

def say_hello():
     print("Hello, friend!")

To run this function:

say_hello()

Example 2: Function with input 

def greet(name):
     print("Hi", name)
greet("Blackmare01wolf") # Output: Hi Blackmare01wolf

Example 3: Function that gives back a result 

def add(a, b):
     return a + b
total = add(5, 10)
print(total) # Output: 15

Use def to define a function. Use return when you want to give back a value.