Non-functional requirements (NFRs) refer to the characteristics or qualities of software that do not relate to its specific functionality. These requirements represent the quality attributes of a system and define its overall aspects such as performance, scalability, reliability, usability, accessibility, maintainability, and more.
Examples:
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Performance: The system should carry out tasks within an expected response time, resource utilization, and throughput rate.
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Scalability: The system should handle increasing amounts of users, data, and tasks, while maintaining its performance.
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Reliability: The system should be working well enough, even when showing indications of deteriorating performance.
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Usability: This system should provide user interfaces and user experiences that help end-users succeed.
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Accessibility: The system should work well for people with disabilities, and also satisfy legal and ethical obligations.
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Maintainability: The system should be easily accessible for maintenance, and also maintenance costs should be low.
Non-functional requirements are critical to ensure the success of the system. By including non-functional requirements in the software development process, businesses can ensure that their software meets the expectations of stakeholders and end-users.