Behavioral design pattern

Design patterns help us to create robust applications by solving common problems using known and proven solutions.

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 Strategy design pattern helps to define different behaviors or functionalities that can be changed at runtime.

In the Strategy pattern, we create different classes that represent strategies and that we can use, according to some variation or input.