Python Basics: Variables, Loops and Functions

Nearly everything in programming comes down to three ideas. Learn these in Python and you’ll recognise them in every other language you meet.

Variables — boxes with names

A variable is a name that points at a value.

name = "Shahid"
age = 22
price = 1099.99

You read it as “name is now "Shahid"”. The = means assign, not equals.

Loops — doing something repeatedly

A for loop repeats a block of code, once for each item in a list.

games = ["pong", "tetris", "zelda"]

for game in games:
    print("Loaded", game)

The indented lines are the body of the loop — everything indented runs once per item.

Functions — reusable recipes

A function bundles instructions under a name so you can call them anytime.

def greet(person):
    return "Hey " + person

print(greet("Shahid"))

def defines the function, person is an input, and return hands a value back. Call it with different inputs and you get different outputs.

Conditions — making choices

price = 1099
if price > 1000:
    print("Big purchase!")
else:
    print("Nice and cheap.")

if checks a condition and runs one branch or the other.

Put it together

def total(cart):
    return sum(cart)

items = [300, 450, 850]
print("Total:", total(items))

That’s a real, useful program: a function, a list and a loop working together. Everything else you learn is just these three ideas wearing different hats.