is

In Python, the is keyword lets you test for object identity. Unlike the equality operator ==, which checks if the values of two objects are the same, is checks whether two variables point to the same object in memory. This distinction is crucial when you need to know if two references are actually pointing to the exact same object.

Python is Keyword Examples

Here’s a quick example demonstrating the use of the is keyword:

Python 
>>> a = [1, 2, 3]
>>> b = a
>>> c = [1, 2, 3]

>>> a is b
True

>>> a is c
False

>>> a == c
True

In this example, a and b both refer to the same list object, so a is b returns True. However, a and c are two distinct objects with the same content, so a is c returns False. The expression a == c returns True because the lists have the same contents, even though they are different objects.

Python is Keyword Use Cases

  • Checking whether two variables refer to the same object
  • Determining if a variable is None using is None
Python Pit Stop

Tutorial

Python != Is Not is not: Comparing Objects in Python

In this quick and practical tutorial, you'll learn when to use the Python is, is not, == and != operators. You'll see what these comparison operators do under the hood, dive into some quirks of object identity and interning, and define a custom class.

intermediate best-practices python

For additional information on related topics, take a look at the following resources:

By Leodanis Pozo Ramos • Updated Jan. 6, 2025 • Reviewed by Dan Bader
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