In python, is is used to check for identity and == is used to check for equality.
is will return True if two variables point to the same object.
== will return True if the objects referred to by the variables are equal.

list2 is list1 returned True because both list1 and list2 refer to the same object as they have the same memory address (on this machine, it is 0x2faaf857e00)

list2 is list1 returned False because list1 and list2 are different object and they have different memory addresses (on this machine, list1 is stored at 0x2faaf896300 and list2 at 0x2faaf900dc0)

List2 == list1 returned True because both list1 and list 2 have the same value (in this example, [1, 2, 3])

List2 == list1 returned True because both list1 and list 2 have the same value (in this example, [1, 2, 3])

The operator is and its counterpart is not are used for checking object identity, they check if objects refer to the same instance (same address in memory).
The operator == and its counterpart != are used for checking equality (same value), they check if objects have same value or not.

As a rule of thumb, a is b implies a == b (except for odd things like floating point NaNs that compare inequal to themselves).

• a == b does not imply a is b.
• Operator is cannot be overloaded.
• Operator == can be overloaded.

Small integers (-5 to 256) behaves differently because CPython implementation optimizes the storage of integers in the range (-5 to 256) by making them singletons. Each (small) integer value is mapped to a single value, so every 3 is identical and equal. This is an implementation detail, not part of the language specification.

Comparisons to singletons like None should always be done with is or is not, never the equality operators

== is typically used to see equality of

• integers
• floats
• strings
• lists
• sets
• dictionaries