Internal vs. External Quality

Internal vs external quality OR why software design matters.
 Internal quality (known bugs, code quality, design, extensibility, refactoring) doesn't matter to the customer NOW. The customer may not be able to conduct any (blockbox) tests to determine the internal quality of the software anyhow, so it may as well not exist.
So... marketing/management may be tempted to concur.
They would be wrong... because, in time code quality impacts the bug rates, performance, cost of development of new features, and time to market for new features. The current code base results in debt. Like all debt, you can pay off the principal early or pay off the interest on an ongoing base. Either decision is fine in some circumstances, as long as it is the right decision for the organization
==> more important to keep the changing and critical areas 'clean'.

Sources of tech debt
=> some debt is taken by design
==> some by being reckless
===> and some debt is only visible in retrospective as we learn more about the problem space.