If you ask a beginner what the difference is between is and ==, you'll often hear something like `==` compares values, while `is` compares references.

Python divides all objects into two large groups. The first group is called mutable objects. The second is immutable objects.

It almost looks as if Python somehow 'links' variables together. But that's not what's happening.

In the previous article, we learned that variables in Python don't store data themselves. Instead, a name simply refers to an object. With numbers, this feels quite intuitive. But as soon as we start working with lists, Python's behavior often surprises people.

At first glance it sounds obvious. We imagine a variable as a box in memory where you put a value. But Python works a little differently - and understanding that difference explains a lot.