What actually distinguishes a good application from a mediocre or bad one? From the user's point of view it is certainly the efficiency of the processes, the user guidance within the application, an intuitive usability and of course in general the design and performance.
For developers and also the decision maker or project manager there is another important unit of measurement to evaluate the quality of a software, namely the general code quality. Have coding standards been adhered to and have even the rather trivial case scenarios been covered? In order to keep the quality standard as high as possible and to continuously improve the source code, the software development process includes testing all areas of the software for perfect functionality and, of course, for security.