Specific users could be janitors, doctors, nurses, technicians, buyers, sellers, etc. while specific context of use would include their task at hand, and goal they are trying to accomplish. Obviously a doctor may have different behavior and usage patterns than a nurse, even though they may be trying to accomplish the same task. They may be more prone to errors since they don’t use the prescription filling software (for example) as frequently as the nurse. So these ‘specific users’ and ‘specific contexts’ need to be accounted for when evaluating the quality right? Beauty is in the eyes of the beholder and so is quality!
In summary, the definition for software quality leads to how you will evaluate software quality. And, QinU is an important part of that definition. In simple terms, it doesn’t matter how beautiful the design is, if there are ‘zero defects’, or how well the software performs (meeting non-functional requirements) if users cannot accomplish their tasks successfully!
[1.] ISO/IEC CD 25010 Software engineering — Software product Quality Requirements and Evaluation (SQuaRE) — Quality model and guide, 2009.