According to IEEE, quality assurance is defined as "a planned and systematic pattern of all actions necessary to provide adequate confidence that an item or product conforms to established technical requirements." Quality assurance (QA) can be broken down into two main areas: product assurance and process assurance.
Product assurance involves making sure that the final product meets its specifications. This is usually done via thorough testing. Ideally, it also includes verifying that the requirements are correct, the design meets the requirements, and the implementation reflects the design.
Process assurance looks at the process used to create that final product. Was the development effort planned? Were the plans followed, or just put on the shelf and ignored? Does the development process meet any required standards? Are best practices used to develop the product? In process assurance, QA provides management with objective feedback regarding compliance to approved plans, procedures, standards, and analyses.
Process assurance activities are performed throughout the life cycle, including product conception, design, implementation, operation, and maintenance. Process assurance will detect, record, evaluate, approve, track and resolve deviations from approved plans and procedures. For each life cycle phase, process assurance makes sure that planning is performed, that the plan is followed, and that the products of each phase are correct and complete. Note that verifying the quality of the requirements, design, and verifications are usually considered product assurance. This course includes them in process assurance because they are often overlooked when evaluating complex electronics.
For a circuit board that is assembled, product assurance would include verifying that the correct parts are on the board, assessing the quality of the soldering, and testing the board functionality. Process assurance activities would include verifying that the drawing used during the board assembly was configuration controlled and the correct revision, that proper Electrostatic Discharge (ESD) requirements were followed, and that an assembly process was defined and followed.