When does automatic memory release occur with garbage collector?

In Python, automatic memory release by an object occurs when there are no more references to it in the program — that is, the object becomes unreachable. The garbage collector detects such objects and frees the memory allocated for them.

Main cases:

• When variables containing a reference to the object go out of scope.
• When references to the object are overridden or deleted.
• When cyclic references are detected that are unreachable from root objects (for example, through the cyclic garbage collector mechanism).

Example:

class MyClass:
    pass

obj = MyClass()  # Create an object
obj = None       # Reference is removed, object becomes unreachable
# Garbage collector will automatically free the memory