ABSTRACT
Software can be characterized by any of a number of qualities. External qualities are those that are visible, such as usability and reliability, and are of concern to the end user. Internal qualities are those that may not be necessarily visible to the user, but help the developers to achieve improvement in external qualities. For example, good requirements and design documentation might not be seen by the typical user, but these are necessary to achieve improvement in most of the external qualities. A specific distinction between whether a particular quality is external or internal is not often made because these qualities are so closely tied. Moreover, the distinction is largely a function of the software itself and the kind of user involved.
