What Are Identity Operators in Python?

In Python, identity operators check whether two variables refer to the same object in memory.
This is different from equality (==), which checks if the values are the same.

Python has two identity operators:

OperatorMeaning
isTrue if both variables reference the same object
is notTrue if both variables reference different objects

Why Identity Matters

Python variables are names bound to objects, and two variables can have the same value but refer to different objects in memory.
Identity operators tell us whether the object itself is the same, not just the value.

Examples of Identity Operators (with Input & Output Together)

1. is Operator

Python 
x = 5 y = 5 print(x is y) # Output: # True

Here, small integers are interned (cached by Python), so x and y reference the same object.

2. is not Operator

Python 
a = [1, 2, 3] b = [1, 2, 3] print(a is not b) # Output: # True

Although a and b have the same value, they are different objects in memory.

Identity vs Equality

The == operator checks value equality, whereas is checks identity

Python 
a = [4, 5, 6] b = [4, 5, 6] print(a == b) print(a is b) # Output: # True # False

  • a == b → True (same contents)

  • a is b → False (different objects)

When Identity Can Be Useful

Identity operators are often used to check for special singleton objects like None

Python 
result = None if result is None: print("No result found") # Output: # No result found

Using is None is a Python best practice for checking absence of a value.

How Python Stores Small Objects

Python interns (caches) some small immutable objects like:

  • Small integers

  • Short strings
    In these cases, is might evaluate to True for variables with the same literal values.

Example:

Python 
a = "hello" b = "hello" print(a is b) # Output: # True

This works because Python may store one copy of the literal and reuse it.