It is difficult to evaluate something unmeasurable, for example, quality of a software product. Many various metrics, standards and rates have been elaborated for this purpose.

One can receive a good vision of an application exploring different aspects of its quality.

Usually the Next Elements of Application Quality are Considered:

1. Correctness of the software product. It shows to what extent the application functions properly and how many software bugs are per number of code lines.
2. Maintainability of the application. It demonstrates how easy it is to find, to determine and to fix the errors. Here metric Mean Time to Change is utilized. It shows how much time takes determining the cause of a reported error and fixing it.
3. Integrity of the tested program. This aspect is explored during security testing. Checking this aspect testers verify likelihood of attacks on the application and likelihood of successful resistance to the attacks.
4. Application usability. In course of usability testing one considers what skills and knowledge a user must have for work with the program; how much time is needed for a user to puzzle out how to work with the software; what advantages the program has in comparison with similar products; opinion of end-users about the program.

A software testing company claims that these 4 elements allow to evaluate an application and must be considered during mobile application testing, desktop testing or web site testing.