Software Architect's Handbook

External or internal

Quality attributes can be internal or external. Internal quality attributes can be measured by the software system itself and are visible to the development team. Consequently, they are measurable both during and after development. Examples of internal quality attributes are aspects of the software system such as lines of code (LOC), level of cohesion, readability of the code, and the degree of coupling between modules.

These attributes reflect the complexity of the software system. Although internal quality attributes are not visible to users directly, they affect external quality attributes. A greater level of internal quality often leads to a greater level of external quality.

External quality attributes are properties ...