Two words people mix up
Quality control (QC) is the part you can picture: analysts in a lab weighing tablets, running an assay, reading a dissolution result, deciding whether a batch passes. It is product-focused and largely about measurement. Quality assurance (QA) is broader and quieter: it is the whole management system that makes sure things are done right the first time — approved procedures, trained people, validated methods, controlled documents, investigations when something goes wrong. QC answers “did this batch pass?” QA answers “can we trust how we got that answer, and would we have caught it if it hadn't?”
Why you cannot test quality into a product
Here is the uncomfortable arithmetic. A batch might be a million tablets. You destroy a tablet to test it, so you can only sample a tiny handful. If a problem affects, say, 1% of units, a sample of 20 will probably miss it entirely. End-of-line testing is a coarse net. The deeper answer is to control the process so the problem never arises — and to watch the process while it runs, not only the product after it is finished.
That is the role of in-process control: checks taken during manufacture (tablet weight every few minutes, granule moisture, blend uniformity) so a drift is caught and corrected in real time. And it is the philosophy of Quality by Design (QbD): identify each critical quality attribute — the properties that truly matter to the patient — then design the formula and process so they are reliably met, rather than hoping a final test rescues you.
GMP: the floor everyone stands on
Good Manufacturing Practice (GMP) is the legal baseline that turns these ideas into binding rules: clean facilities, calibrated equipment, written and followed procedures, traceability, and — crucially — records. The batch record is the documented life story of one batch: what was weighed, by whom, on which machine, with which in-process results. If it is not written down, regulators treat it as not done. Process validation is the proof, gathered in advance, that a process run as documented will reliably produce conforming product.
Put together: GMP and QA build the conditions, QbD designs quality in, in-process control watches it happen, and QC confirms the result. A lone passing assay number means little if you cannot show the system that produced it was in control. With that frame in place, the rest of this track zooms into the individual tests.