Have you ever seen a class that fetches data from the database, formats it for the UI, logs the result, and also sends a notification?

Or worked with a function that handles validation, business logic, database access, and exception handling, all in one place?

If so, you’ve witnessed a violation of Separation of Concerns (SoC), one of the most important architectural principles in software engineering.

In this chapter, we’ll explore what SoC really means, why it matters, how to apply it, and how it leads to cleaner, more testable, and maintainable code.