QA, QC, and testing are often treated as synonyms, but they address different questions: how quality is built into work, how it is controlled, and how the product is examined. Understanding the distinction helps clarify responsibilities.
What is QA?
Quality assurance prevents problems through development processes, practices, and systems. It includes quality gates, requirements work, the definition of done, reviews, test strategy, and other practices that prevent widespread defects.
What is QC?
Quality control evaluates the completed product against expectations, requirements, and acceptable risk. Testing is often part of QC, but QC extends beyond one test suite.
What is testing?
Testing is the concrete work of investigating and checking a product: analysis, design, execution, observation, and result recording. Testing supports QC, which belongs within the broader QA system.
One example across all three
- →QA: the team agrees readiness criteria and reviews requirements before development.
- →QC: before release, the team evaluates whether critical risks are addressed and testing scope is sufficient.
- →Testing: a tester exercises scenarios, checks APIs, UI, and data, and records defects.
Why job titles overlap
A QA Engineer, Test Engineer, or QC Engineer may perform a mixture of process work, testing, and quality control. Actual responsibilities matter more than the title.
Practical takeaway
QA builds a system for preventing problems, QC evaluates the resulting quality, and testing supplies evidence for that evaluation. Strong practitioners usually contribute to all three to different degrees.