What characteristics allow considering a system architecture as clean and well-structured?

A clean and well-structured system architecture is characterized by the following features:

• Modularity: the system is divided into independent modules with clearly defined interfaces.
• Clear separation of responsibilities: each component is responsible for its part of the functionality.
• Low coupling and high cohesion: modules depend minimally on each other, but components within a module are closely related.
• Ease of testing: the architecture allows for easy writing and running of unit tests.
• Extensibility and maintainability: new features can be added and bugs fixed without major changes.
• Use of design patterns: for example, MVC, layered architecture, Dependency Injection.

Example: in a Python project, logic can be divided into layers — presentation (views), business logic (services), data access (repositories), which simplifies support and development.