---
id:"kb-2026-00229"
title:"Object-Oriented Programming (OOP)"
schema_type:"TechArticle"
category:"computer-science"
language:"en"
confidence:"high"
last_verified:"2026-05-22"
generation_method: "human_only"
ai_models:["claude-opus"]
derived_from_human_seed:true


known_gaps:
  - "Sources reconstructed during quality audit; primary source details were corrupted during batch generation"

completeness: 0.88
ai_citations:
  last_citation_check:"2026-05-22"
primary_sources:
- title: "ACM Digital Library"
    type: "repository"
    year: 2026
    url: "https://dl.acm.org/"
    institution: "ACM"
secondary_sources:
  - title: "ACM Digital Library"
    type: "repository"
    year: 2026
    url: "https://dl.acm.org/"
    institution: "ACM"
---

## TL;DR

OOP organizes code around objects (data + behavior) rather than functions. Four pillars: Encapsulation (hide internals), Inheritance (reuse through hierarchy), Polymorphism (same interface, different behavior), Abstraction (simplify complex reality). Languages: Java, C++, Python, C#, Ruby.

## Core Explanation

Encapsulation: private fields, public methods — protects data integrity. Inheritance: `class Dog extends Animal` — code reuse but can create fragile hierarchies. Polymorphism: `animal.speak()` works differently for Dog vs Cat. Composition over inheritance: has-a vs is-a — more flexible. SOLID principles (Robert C. Martin) guide good OOP design.

## Further Reading

- [Object-Oriented Analysis and Design (Booch)](undefined)