FURPS

FURPS is an acronym representing a model for classifying software quality attributes :

Functionality - capability, reusability, security
Usability - human factors, aesthetics, consistency, documentation, responsiveness
Reliability - availability, failure extent and time-length ), predictability, accuracy
Performance - speed, efficiency, resource consumption, throughput, capacity, scalability
Supportability - testability, flexibility, installability, localizability

The model, developed at Hewlett-Packard was first publicly elaborated by Grady and Caswell. FURPS+ is now widely used in the software industry. The + was later added to the model after various campaigns at HP to extend the acronym to emphasize various attributes, such as Design Requirements, Implementation Requirements, Interface Requirements and Physical Requirements.