What is the purpose of using `self` in Python classes?

Using self in Python classes serves a crucial purpose, as it refers to the instance of the class upon which a method is being called. When a method is defined within a class, self allows that method to access attributes and other methods associated with the specific instance of the class. This is essential for maintaining state and behavior that is unique to each object created from the class.

When you create an object from a class, that object holds its own data. By using self, the methods within the class can operate on that data. For example, if an instance variable is set using self, it allows each instance to have its own value for that variable, thereby enabling encapsulation and object-oriented programming principles.

In summary, self is vital for differentiating between different instances of a class, ensuring that methods and behaviors relate to the individual object rather than the class as a whole. This is a foundational concept in object-oriented programming, allowing for clearer structure and better organization in code.