FURPS

FURPS is an acronym representing a model for classifying software quality attributes (functional and non-functional requirements):


 * Functionality - Capability (Size & Generality of Feature Set), Reusability (Compatibility, Interoperability, Portability), Security (Safety & Exploitability)
 * Usability (UX) - Human Factors, Aesthetics, Consistency, Documentation, Responsiveness
 * Reliability - Availability (Failure Frequency (Robustness/Durability/Resilience), Failure Extent & Time-Length (Recoverability/Survivability)), Predictability (Stability), Accuracy (Frequency/Severity of Error)
 * Performance - Speed, Efficiency, Resource Consumption (power, ram, cache, etc.), Throughput, Capacity, Scalability
 * Supportability (Serviceability, Maintainability, Sustainability, Repair Speed) - Testability, Flexibility (Modifiability, Configurability, Adaptability, Extensibility, Modularity), 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.