# O - Open Closed (OCP) ## About Classes should be open to extension and closed for modification. *The behavior of a module can be extended without modifying its source code.* Whenever you need to add new functionality to a class, don't just modify the existent class. Instead create a base class, and for each added functionality you make it in a new class to extend the base one. {% hint style="info" %} Using Factories to create similar implementations. {% endhint %}