Principle

Use it when you anticipate that a class or module will have many variations and will be used in multiple places.

Used to break down large interfaces into smaller ones for easier maintenance and extension.

When adhering to this principle, derived classes should be substitutable for their base classes without altering the correctness of the program.

The Open-Closed Principle (OCP) is used to achieve an extensible design for maintaining modules or classes. The principle itself applies to both classes and modules.

Use when you estimate the class can be reused in many places and has the potential for extension.

The overview of SOLID.