---
id:"kb-2026-00239"
title:"SOLID Principles"
schema_type:"TechArticle"
category:"computer-science"
language:"en"
confidence:"high"
last_verified:"2026-05-22"
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ai_citations:
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    url: "https://dl.acm.org/"
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secondary_sources:
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---

## TL;DR

SOLID (Robert C. Martin, 2000s) is five principles for object-oriented design: S (Single Responsibility), O (Open/Closed), L (Liskov Substitution), I (Interface Segregation), D (Dependency Inversion). SOLID makes code more maintainable, testable, and flexible.

## Core Explanation

SRP: a class should have one reason to change. OCP: open for extension, closed for modification — add behavior without changing existing code. LSP: subtypes must be substitutable for base types. ISP: many specific interfaces better than one general interface. DIP: depend on abstractions, not concretions — high-level modules shouldn't depend on low-level details.

## Further Reading

- [Agile Software Development (Robert C. Martin)](undefined)