What is the role of layers in structuring Clean Architecture?

In Clean Architecture, layers serve to separate responsibilities and simplify code maintenance. The main layers:

• Entities — business logic and rules, independent of external details.
• Use Cases — implementation of specific usage scenarios, interacting with entities.
• Interface Adapters — data transformation between layers, such as converting models into formats suitable for UI or databases.
• Frameworks and Drivers — external components like databases, UI, network services.

Each layer depends only on the inner layers, which ensures loose coupling and facilitates testing and component replacement. For example, business logic does not depend on the UI, allowing the interface to be changed without modifying the core application.