改变语言顺序：观察者模式是一种行为型设计模式，它定义了一种一对多的对象依赖关系，当一个对象的状态发生变化时，所有依赖于它的对象都会得到通知并自动更新。

Observer Pattern is a behavioral design pattern that defines a one-to-many dependency between objects, so that when one object changes its state, all the objects dependent on it are notified and updated automatically. The purpose of the Observer Pattern is to establish communication between objects in a loosely coupled way, allowing for flexibility and extensibility in the system.