How is the principle of data encapsulation achieved in Python?

In Python, encapsulation is achieved through naming conventions and special mechanisms:

• Single underscore (_var) — indicates that the field or method is protected, meaning it is not intended for use outside the class or its subclasses.
• Double underscores (__var) — invoke name mangling, which makes external access more difficult, simulating privacy.

Example:

class MyClass:
    def __init__(self):
        self.public = 1
        self._protected = 2
        self.__private = 3

obj = MyClass()
print(obj.public)       # 1
print(obj._protected)   # 2 (but it is not recommended to use)
# print(obj.__private)  # AttributeError error
print(obj._MyClass__private)  # 3 (access via mangling)

Thus, encapsulation in Python is based on conventions and mangling mechanisms, not on strict restrictions like in some other languages.