- define system properties and constraints e.g. reliability, usability, response time etc. - can be product (e.g. performance), organisational (e.g. authentication) or external (e.g. legal)
- define system properties and constraints e.g. reliability, usability, response time etc. - can be product (e.g. performance), organisational (e.g. authentication) or external (e.g. legal)
attributes of the system not needed to make the system functional but to enhance its service. example: performance, security, quality, maintainability, extensibility