Quality

In software terminology, quality has a very specific meaning: how suited is a given application or component to purpose - i.e. does it fulfill pre-defined or expected requirements? Furthermore, quality can refer to the level to which a given software product conforms to customers' expectations and satisfies their needs. Lastly, quality can refer to the degree to which a particular line of code fulfils requirements in terms of its inherrent points.

Cf. Wikipedia on quality.

Quality attributes/characteristics

These are the characteristics and features of a software application on which judgements of quality are based. Depending on purpose, attributes can either be spoken about in parts or as whole categories; in some usages, quality attributes may simply be referred to totem pro parte as "quality"

See Wikipedia for more information on software quality norms such as ISO/IEC 9126.

Quality control

In contrast to quality assurance (e.g. constructive and analytical QA), quality control is focussed on checking quality after development, the aim being to show that the product fulfills the requirements formulated at the beginning of the development process.

Both QA and QC are part of the quality management system (Wikipedia).