What does the "feature isolation" principle mean?

The "feature isolation" principle in Angular means that each functional part of the application (a feature) is isolated in its own module and does not depend directly on other parts.

The main idea:

1. Self-sufficiency - a module contains all its own components, services, and dependencies to work independently.
2. Minimizing coupling - changes in one module do not break other parts of the application.
3. Reusability - isolated modules can be moved or reused in other projects without extra code.
4. Simplified maintenance and testing - it's easier to find bugs and test specific functionality.

Feature isolation helps build scalable, maintainable, and more reliable applications.