QA vs QC: What's the Difference, and Which Does Your Team Need?

Quality assurance (QA) is process-focused work that prevents defects by improving how software is built, through standards, reviews and test planning. Quality control (QC) is product-focused work that finds defects in what has been built, through testing and inspection. QA prevents problems and QC detects them. Most teams need both.

What is the difference between QA and QC?
ISO 9000 defines quality assurance as focused on providing confidence that quality requirements will be fulfilled, and quality control as focused on fulfilling them. In software terms:

• Focus: QA looks at the process. QC looks at the product.

• Goal: QA prevents defects. QC finds them.

• Timing: QA runs through the whole lifecycle, starting at requirements. QC happens once something is built.

• Examples of QA: coding standards, code review rules, test planning, a clear definition of done, process audits.

• Examples of QC: regression testing, bug verification, exploratory testing, release checks.

Testing is a QC activity. QA is the wider effort that decides how, when and why you test.

Where does quality engineering fit?
Quality engineering joins both and builds them into delivery. Instead of testing at the end, automated checks run in the CI/CD pipeline on every build, and quality rules are agreed before development starts. Our guide to CI/CD pipeline best practices shows where those checks belong, and P99Soft's quality engineering services help teams set this up.

Which do you need first?
Both from the start, but teams often over-invest in QC and under-invest in QA. You probably need more QA if the same bugs keep returning, surprises appear late or requirements are unclear. You probably need more QC if bugs reach customers, there is no regression safety net or releases feel risky. A simple way to begin is to write acceptance criteria before development starts (QA) and automate smoke tests on every build (QC).

What does a basic QA and QC checklist look like?

1. Every requirement has testable acceptance criteria.

2. Code reviews follow shared standards.

3. Automated checks run on every build.

4. Defects are tracked with their root causes.

5. Releases follow a defined sign-off.

For deeper practice, see our guides to end-to-end system testing, cloud and modernization testing and mobile app testing strategy. For where the field is heading, read our software testing trends piece.

FAQs

Is QA the same as testing?
No. Testing finds defects and is a QC activity. QA also covers the processes that stop defects from appearing.

Which is more important, QA or QC?
Neither works well alone. QA lowers how many defects you create, and QC catches the ones that remain.

Can one person do both QA and QC?
Yes, especially in small teams, as long as the work is planned for both prevention and detection.