There are many aspects of "Quality" discussed on this Wiki. The one main aspect that needs to be pointed out is that quality is a measurable phenomenon. As such, we need to discuss how quality is defined in context and how it is measured in such a way as to produce useful comparisons for all members of the team -- this includes such folks as middle level managers, salespeople, marketeers, and Vice Presidents.
I have been working in a SixSigma organization, which has made me think about quality and measurability. I have been looking for, and unable to find, a good definition of software quality. Ditto for measurements of software quality. (That is, aside from rigorous proofs that code will perform as intended, which will be intractable for all but the smallest problems.) Does anyone know of any measurements that could be applied?
One obvious measurement is conformance with acceptance tests (if it does everything that the customer wants correctly, it must be high quality), but the acceptance tests then must provide complete coverage of all possible scenarios, including failure of databases and other connected components.
However, the base definition for quality remains the one proposed by Phil Crosby: Quality is conformance to requirements. The obvious questions raised by that definition are what does it mean to conform, and what are the requirements. The Quality category is a discussion of the answers to these questions.
Wikipedia has also developed some useful resources on this subject: