Instance Variables and Instance Methods in Python

DEV Community

active' if self.is_active else 'not active'}")

Step 1: Creating Objects (Instances)

user1 = User()
user2 = User()

When we execute this:

Python creates two separate objects in memory
Each object has its own space to store data
Both objects have access to all instance methods

Important: Object and Instance mean the same thing.

What Happens Inside Memory?

Even though both objects come from the same class blueprint:

user1 has its own data storage
user2 has its own data storage

They do NOT share instance variables.

This is the beauty of OOP.

Understanding Instance Methods in Action

Now let’s call:

user1.set_email("shameel@hasabtech.com")

What happens?

Python sees user1
It passes user1 automatically as self
Inside method:

self.email = email

Becomes

user1.email = "shameel@hasabtech.com"

Now:

user1 has email
user2 still has nothing

This proves instance variables belong to objects.

Adding More Data to Objects

Now:

user1.activate()
user2.deactivate()

This creates:

user1.is_active = True
user2.is_active = False

Again:

Each object has its own is_active
They are completely independent

This independence is the core idea of instance variables.

Why Methods are Called Instance Methods?

Because they:

Work with instance variables
Depend on the object
Use self to access object data

For example:

def show_status(self):
 print(f"{self.email} is {'active' if self.is_active else 'not active'}")

This method:

Reads self.email
Reads self.is_active
Prints data of that specific object

So this method behaves differently for each object.

That’s why it is called an instance method.

Common Beginner Confusion

Many students think:
Is self a keyword?
No.

self is just a naming convention.

You can write:

def activate(myobject):

def activate(myobject):

But by convention, we always write self

Why This Concept is Very Important?

If you understand instance variables and instance methods, you can:

Build login systems
Create user management systems
Understand Django models
Work with APIs
Design real-world applications

Without understanding self, OOP will feel complicated.

Final Understanding

Whenever:

You attach data using self → It becomes an instance variable.
You define a method with self → It becomes an instance method.

Each object:

Has its own data
Shares method structure
Behaves independently

Summary

Object = Instance. They mean the same thing.
Instance Variables are the "adjectives" (data) that describe the object.
Instance Methods are the "verbs" (actions) the object can perform.
self is the bridge that connects the method to the specific object’s data.
Each object has its own copy of instance variables