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, Predictability, Accuracy
- Performance – Speed, Efficiency, Resource Consumption, Throughput, Capacity, Scalability
- Supportability – Testability, Flexibility, Installability, Localizability
The + was later added to the model to emphasize below attributes.
- Implementation – resource limitations, languages and tools, hardware..
- Interface – constraints imposed by interfacing with external systems.
- Operations – system management in its operational setting.
- Packaging – for example, a physical box.
- Legal – licensing and so forth.
In addition to the functions a system must perform, there are often constraints the system must satisfy. Some constraints may apply to individual use cases. All other requirement other than ‘Functionality’ in above model are non functional requirements.