Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.In the context of software engineering, software quality measures how well software is designed, and how well the software conforms to that design although there are several different definitions. Whereas quality of conformance is concerned with implementation, quality of design measures how valid the design and requirements are in creating a worthwhile product. One of the challenges of Software Quality is that "everyone feels they understand it".