The Observer’s design pattern is used primarily when we are interested in any change of status being notified to anyone who needs to know about that change.
In the observer design pattern, the object that looks at the state of another object is called “Observer” and the object that is “looking” those changes is called “Subject”.
The Factory design pattern is mainly used when we have a class or interface with many subclasses or implementations, and according to some input, we need to return one of these specific subclasses.
The Facade design pattern simplifies the complexity of a system through a simpler interface.
It improves access to our system by allowing other systems or subsystems to use a common access point that reduces complexity, minimizing interactions and dependencies.
The Decorator pattern allows you to add new features to classes without modifying their structure.
The Composite design pattern allows you to create objects from an interface by making them all similar and allowing them all to be treated in the same way.
The Builder design pattern allows you to create objects that are usually complex using another object that builds them step by step.
The Adapter design pattern works when you have different or incompatible interfaces, and you need the client to use both in the same way.
The Adapter design pattern says in its definition that it converts an interface or class into another interface that the client needs.