id

Get the unique number of an object while the object exists.

Python 3.13
id(object)

Parameters

objectAny: Any object.

Return value

An int.

Examples

Two variables, one object

Python 3.13
a = [1, 2]
b = a
print(id(a) == id(b))
True

Equal but different lists

Python 3.13
a = [1, 2]
c = [1, 2]
print(a == c, id(a) == id(c))
True False

Details

id(a) == id(b) is the same as a is b: it is one and the same object. The number itself changes between runs; objects that exist at different times may get the same number.

id