What is the meaning of single and double underscore before an object name?

In Python, a single underscore (_) before an object name is used as a hint to indicate that the object is intended to be private and not part of the public API. This is a convention only and does not enforce any restrictions on accessing the object. A double underscore (__) before an object name triggers name mangling, which makes the object effectively private. Name mangling adds the name of the class to the front of the object name, making it difficult to access from outside the class. Here's an example:

class MyClass:
    def __init__(self):
        self.__private_attribute = 42

    def get_private_attribute(self):
        return self.__private_attribute

my_obj = MyClass()
print(my_obj.__private_attribute) # Raises an AttributeError
print(my_obj._MyClass__private_attribute) # 42