What is a Quality Control (QC)?
Quality control is product-focused and detective: it inspects, measures, and tests actual deliverables against acceptance criteria, catching defects before they reach the customer. Its outputs are verified deliverables — and defect data that feeds back into improving the process.
QC tools are the famous seven: checksheets, Pareto charts, fishbone diagrams, histograms, control charts, scatter diagrams, flowcharts. Remember the pairing: QC finds the defect; QA fixes the process so the defect stops recurring.
Worked example
The QC step on a software release: run the 800-case regression suite, verify the checkout flow against acceptance criteria, log every failure. Then the Pareto chart shows 70% of defects come from the payments module — which triggers a QA conversation about how payments code gets reviewed.