| Pillar | Meaning | Example Phrase |
|---|---|---|
| Encapsulation | Hiding internal state, exposing only an interface | "We encapsulate the payment logic inside the PaymentService class." |
| Inheritance | A class inherits properties/methods from a parent class | "AdminUser inherits from the base User class." |
| Polymorphism | Different classes respond to the same interface differently | "Both SQLRepository and MongoRepository implement the same interface." |
| Abstraction | Hiding complexity behind a simple interface | "The client doesn't need to know how the data is stored." |