Glossary

Clean Architecture

Clean Architecture (Robert Martin) is a principle of organising code into concentric layers where inner layers know nothing about outer ones. Dependencies always point inward — from UI and DB toward business logic, never the other way.

Layers (inner to outer)

Entities — enterprise business rules. Depend on nothing
Use Cases — application business rules. Depend only on Entities
Interface Adapters — Controllers, Presenters, Gateways. Transform data formats between Use Cases and the outside world
Frameworks & Drivers — DB, Web, UI. The outermost layer

The dependency rule

Code in an inner layer never mentions anything from an outer one. Dependency is injected through an interface.

Related concepts

Hexagonal Architecture (Ports & Adapters), Onion Architecture — different names for the same idea: shield domain logic from infrastructure.