Quality control involves testing of units and determining if they are within the specifications for the final product. The purpose of the testing is to determine any needs for corrective actions in the manufacturing process. Good quality control helps companies meet consumer demands for better products.

Quality testing involves each step of the manufacturing process. Employees often begin with the testing of raw materials, pull samples from along the manufacturing line and test the finished product. Testing at the various stages of manufacturing helps identify where a production problem is occurring and the remedial steps it requires to prevent it in the future.

The quality control a business uses is highly dependent on the product. In food and drug manufacturing, quality control includes ensuring the product does not make a consumer sick, so the company performs chemical and microbiological testing of samples from the production line. Because the appearance of prepared food affects consumer perception, the manufacturers may prepare the product according to its package directions for visual inspection. In the automobile manufacturing, quality control focuses on the way that parts fit together and interact and ensuring engines operate smoothly and efficiently. In electronics, testing might involve using meters that measure the flow of electricity.

Quality control inspectors protect the consumer from defective products and the company from damage to its reputation due to inferior manufacturing processes. If the testing process reveals issues with the product, the inspector has the option of fixing the problem himself, returning the product for repairs or tagging the product for rejection. When issues arise, the inspector notifies supervisors and works with them to correct the problem.