OOP is based on 4 pillars:

1. Abstraction: makes process/functionality abstract
2. Polymorphism: one entity, many forms
3. Encapsulation: protect methods and variables
4. Inheritance

There's also OOAD. OOAD is object-oriented analysis and design. It's a technical approach for analyzing an ddesigning an application, system, or business by applying OOP as well as using visual modeling.