Quality Assurance
Also known as: QA
Quality Assurance (QA) is the set of proactive activities aimed at preventing defects before they happen — process design, standards, code review practices, and test planning — as opposed to Quality Control, which is the reactive work of finding defects that already exist. In practice, "QA" is also used loosely as an umbrella term covering both.
The textbook distinction: QA is process-focused and preventive ("are we building this the right way"), QC is product-focused and detective ("does this specific build have defects"). Testing itself — running test cases against a build — is technically QC work under this framework, even though the people doing it are almost universally called "QA engineers" or "the QA team."
In most real organizations this distinction has blurred into irrelevance — "QA" is simply the umbrella term for the discipline covering test strategy, test execution, defect management, and process improvement. Knowing the formal distinction is mostly useful for interviews and for understanding why some job titles say "Quality Engineer" instead of "QA Engineer" — they're gesturing at the same QA-vs-QC split.
