Non-Functional Requirements
Non-functional requirements (NFRs) are criteria that specify how a system should perform, rather than what it should do. They define system qualities such as performance, security, reliability, and usability, which are essential for ensuring the software meets user expectations and operational needs. Unlike functional requirements that describe specific features, NFRs focus on constraints and overall system behavior.
Developers should learn and use non-functional requirements to design robust, scalable, and maintainable software systems, as they directly impact user satisfaction and system success. For example, in e-commerce applications, NFRs like response time under 2 seconds and 99.9% uptime are critical for customer retention and revenue. They are essential in industries such as finance or healthcare, where security and compliance are paramount.