Quality Assurance (QA) is the discipline of making sure software does what it is supposed to do, reliably, before real users depend on it. It is broader than just clicking through a screen looking for bugs. QA covers how work is checked at every step, from the requirements to the final release.
A good analogy is a restaurant kitchen with a head chef tasting every dish before it leaves the pass. The cooking is the development; the tasting, the plating check and the recipe standards are QA. The food still gets made without it, but you find out about the over-salted sauce from the customer instead of the chef. In software, that means writing a clear test plan, turning it into concrete test cases, and re-running checks so a fix in one place does not quietly break another.
QA is not a single moment at the end. It runs alongside the build, which is why bugs caught early cost so much less than ones found by a paying customer at 9am on a Monday.
A practical mix usually works best. Automated tests guard the boring, repeatable paths, like login or checkout, and run on every code change so a regression gets flagged within minutes. Humans then judge the things a script cannot: does this flow feel right, is the error message clear, did we actually build what the client asked for. The deepest pitfall is treating a green test suite as proof of quality. Tests only check what someone thought to write, so a perfectly passing build can still ship a feature nobody really wanted.
At TopDevs we treat QA as part of how we build, not a box ticked at the end, so the software you launch behaves the way it did in the demo.
