General, abstract definitions of quality have often been attempted. The concept may be discussed for long and may give rise to different, subjective formulations, each of them acceptable on the basis of some points of view. What is interesting here, is that precisely defined models can be proposed for quality. A quality model is a very general concept: it can be conceived as a structured set of properties, or characteristics, that can be established for an object to declare it a quality object. The model can be used as a guideline for developing an object or a reference to evaluate properties of a software system.
For software systems, various quality models have been explicitly or implicitly proposed (by Bogen, Deutsch, Azuma, Rae, et.al.). All of them address a methodology to define a hierarchic structure of characteristics and a way to relate these characteristics to some technical aspects of the system. In literature, there is little evidence of showing whether or not the characteristics depend on the application domain the system belongs to. This point is even purposely avoided, probably due to searching for a model as general as possible. In fact, these and other efforts have led to define and approve a very popular standard for software system quality, like the ISO/IEC 9126 resp. ISO14598 or the QoS frameworks and guidelines.
The model referred by this standard defines quality as a set of six characteristics (Functionality, Reliability, Usability, Maintainability, Efficiency, Portability) and proposes a further decomposition of each characteristic into a set of sub-characteristic, wisely not included in the standard. Among the great variety of software products, web portal have widely grown both in the number of media and technologies involved and in the target which they are addressed to.
Speaker Bio to be added later