Similarly, a high level of internal due diligence and quality assurance supports these rankings.
(QA) A planned and systematic pattern of all actions necessary to provide adequate confidence that the product optimally fulfils customers' expectations, i.e. that it is problem-free and well able to perform the task it was designed for.
The QA of a commercial product usually involves alpha testing, where an early version of the product is tested at the developer's site, and is then improved accordingly. Then, an almost complete version of the product is made available for beta testing by (selected) real users. Faults identified during beta testing should be fixed before the product is released for full scale manufacturing and distribution.