It involves techniques to evaluate needs, build in quality, and assess the degree of success. It is a team effort involving engineers, managers, QA staff and others.
Software quality includes activities related to the product and to the process.
QC or control activities are work product oriented. They evaluate the product, identify weaknesses and suggest improvements. The product may be changed as a direct result of these activities. Testing and reviews are examples of QC activities since they usually result in changes to the product, not the process. QA activities focus on the actual development process.