What is SOLID Principles? — UK Software Development Guide

4 min readJune 2025ClickMasters Technical TeamReviewed by James Whitmore, CTO
what are solid principles

Direct Answer

SOLID is an acronym representing five design principles for object-oriented programming: Single Responsibility Principle (a class should have only one reason to change), Open/Closed Principle (open for extension, closed for modification), Liskov Substitution Principle (subtypes must be substitutable for their base types), Interface Segregation Principle (no client should depend on methods it doesn't use), and Dependency Inversion Principle (depend on abstractions, not implementations).

Solid-principles in the UK

SOLID principles are relevant to UK software quality and maintainability. Technical debt — often caused by violating SOLID principles — is the primary reason UK businesses seek legacy modernisation and software rescue services. ClickMasters code reviews assess SOLID adherence as part of our quality standards. For UK regulated software: SOLID-compliant code is more testable (important for QA coverage requirements in HealthTech and FinTech), more maintainable (important for Cyber Essentials patch management), and more auditable (important for ICO accountability requirements).

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