Readable structure, useful tests and understandable dependencies can help developers inspect behavior and make changes. Quality is not just a formatting score; it includes whether the implementation serves its requirements reliably.
The appropriate effort depends on the consequences of failure and the software's expected life. A short-lived prototype and a long-lived critical system may need different levels of assurance, while both still need clear expectations.
ELI5
Code quality is about whether a program's instructions work well and can be understood and changed. Neat formatting alone does not settle it.
For example, a clearly organized calculation with tests is easier to update safely than a mysterious formula copied into several places.
Is quality only about style rules?
No. Style can help readability, but correctness, behavior, dependencies and maintainability also matter.
Does every program need the same amount of engineering effort?
No. Requirements, expected lifetime and the effects of failure influence how much verification and maintenance support are appropriate.
