Let's break this down:

Classes vs Objects

A class is like a blueprint or template that defines what data and behaviors an object will have. In our example, User is a class.

An object (also called an instance) is a specific realization of a class with actual values. user1 and user2 are objects of the User class.

The `init` Method

The __init__ method is a special method in Python classes, known as a constructor. It's automatically called when you create a new instance of a class. The self parameter refers to the instance being created.

Attributes

Attributes are variables that belong to a class or instance. In our example:

self.name and self.email are instance attributes
Each object has its own copy of these attributes with their own values

Methods

Methods are functions that belong to a class and define what actions an object can perform. In our example:

send_notification is a method that takes a message and prints it