What is the difference between == and is in Python?

In Python, the distinction between == and is is fundamental for understanding how comparisons are made between objects. The == operator is used to check for value equality. This means it evaluates whether the values contained in the objects being compared are the same, regardless of whether the two objects are actually the same instance in memory. For example, two different lists containing the same elements [1, 2, 3] will be considered equal when using ==.

On the other hand, the is operator checks for object identity. This comparison determines whether two references point to the same object in memory. If two objects are identical in the sense that they are the exact same instance, is will return True. For instance, if you create a list and assign it to a variable, and then create another variable pointing to the same list, they will be identical:

list_a = [1, 2, 3]

list_b = list_a

list_a is list_b  # This returns True since both variables refer to the same list object.

In summary, memory locations and value contents differ between the two operators: == is for comparing the values within the objects