Learn Python
Step by Step

Python is a high-level, interpreted programming language. "High-level" means it reads closer to English than to machine code, and "interpreted" means you can run your code directly without a separate compile step. That combination is a big part of why beginners pick it up so quickly.

Why Python is a great first language

• Simple, readable syntax that looks almost like plain English
• A huge community and library ecosystem, so help and ready-made tools are everywhere
• Versatility: web apps, AI, automation, data analysis, games, and more all use Python

Editor options

• IDLE: comes bundled with Python, zero setup, perfect for your very first programs
• VS Code: lightweight, powerful, and the most popular choice for real work
• PyCharm: feature-rich and built specifically for Python

Open your editor, create a file called hello.py, and type this single line:

print("Hello, world!")

Save the file and run it. You should see:

That is a complete Python program. The print() function displays whatever you put inside the parentheses. The text in quotes is called a string, which is just programming-speak for a piece of text.

A variable is a name that stores a value so you can use it later. In Python you create one just by assigning a value with =. You never have to declare the type up front, Python figures it out for you.

name = "Alice"      # String  (text)
age = 25            # Integer (whole number)
height = 5.5        # Float   (decimal number)
is_student = True   # Boolean (True or False)

The core built-in types

Operators let you work with values. There are three groups you will use constantly.

Arithmetic, comparison, and logical

x = 10
y = 3

print(x + y)    # 13   addition
print(x / y)    # 3.333...  true division
print(x // y)   # 3    floor division (drops the remainder)
print(x % y)    # 1    modulo (the remainder)
print(x ** y)   # 1000 exponent (10 to the power 3)

Control flow lets your program make decisions. An if statement runs a block of code only when a condition is true.

num = 7

if num > 0:
    print("Positive")
elif num == 0:
    print("Zero")
else:
    print("Negative")

Loops repeat a block of code. Use a for loop when you know how many times to repeat or want to go through a collection, and a while loop when you want to repeat until a condition changes.

The for loop

for i in range(5):
    print(i)

range(5) produces the numbers 0 up to (but not including) 5. This off-by-one detail trips up almost every beginner, so keep it in mind.

The while loop

count = 0
while count < 3:
    print(count)
    count += 1   # same as: count = count + 1

A function is a reusable block of code you can call by name. Functions keep your programs organised and save you from repeating yourself.

def greet(name):
    print("Hello, " + name)

greet("Alice")   # Hello, Alice

Functions can also return a value, which you can store or use elsewhere:

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

result = add(3, 4)
print(result)   # 7

These are Python's everyday containers for holding multiple values. Choosing the right one is a real skill, so here is when to reach for each.

Lists: ordered and changeable

fruits = ["apple", "banana", "cherry"]
print(fruits[0])      # apple  (indexing starts at 0)
fruits.append("mango") # add an item to the end

Tuples: ordered but fixed

colors = ("red", "green", "blue")
# colors[0] = "yellow"  would cause an error, tuples can't change

Use a tuple when the collection should never change, like coordinates or RGB colour values. The fact that it cannot change is a feature, not a limitation.

Dictionaries: key-value pairs

person = {"name": "Alice", "age": 25}
print(person["name"])   # Alice
person["city"] = "London"  # add a new key

Programs sometimes hit problems: a file is missing, a user types text where a number was expected, or you accidentally divide by zero. Error handling lets your program respond gracefully instead of crashing.

try:
    x = 5 / 0
except ZeroDivisionError:
    print("You can't divide by zero!")
finally:
    print("Execution complete.")

The try block holds code that might fail. If it does, the matching except block runs instead of the program crashing. The optional finally block always runs, whether or not an error happened, which makes it useful for cleanup.

Reading and writing files lets your programs save data and load it back later. The with statement is the recommended way because it closes the file for you automatically, even if something goes wrong.

with open("example.txt", "w") as f:
    f.write("Hello from Python!")

with open("example.txt", "r") as f:
    content = f.read()
    print(content)   # Hello from Python!

The second argument is the mode: "w" writes (and overwrites), "r" reads, and "a" appends to the end of an existing file.

Object-Oriented Programming (OOP) is a way of structuring code around objects that bundle data and behaviour together. It is how larger Python programs stay organised.

class Person:
    def __init__(self, name):
        self.name = name

    def greet(self):
        print("Hello, my name is", self.name)

p = Person("Alice")
p.greet()   # Hello, my name is Alice

The key ideas

• Class: a blueprint that describes what an object looks like and can do
• Object: an actual thing created from that blueprint (here, p)
• __init__: the constructor, which runs automatically when you create an object
• self: refers to the specific object, so each one keeps its own data
• Method: a function that belongs to a class (like greet)

Once you are comfortable with the basics, these standard library modules and third-party packages are the natural next things to explore:

Tips for learning Python well

• Practice regularly by building small projects, not just reading
• Read other people's code: GitHub is a great place to start
• Visualise how code runs with a tool like Python Tutor when something confuses you
• Work through coding challenges to cement what you have learned