This is the fourth article on SOLID principles which I started a few weeks ago. I hope this is useful for you and that it gives you a simple understanding of what the Open/Closed principle is all about.
What is the Open Closed principle?
Bertrand Meyer coined the term Open/Closed Principle which appeared in his book titled Object Oriented Software Construction in 1988. The principle reads “software entities (classes, modules, functions, etc.) should be open for extension, but closed for modification“. … An introduction to Open Closed principle (OCP)