What is the focus of non-functional requirements?

Non-functional requirements focus primarily on how a system behaves under various conditions rather than what the system does. This includes aspects such as performance, security, reliability, scalability, and usability. For example, a non-functional requirement might specify that an application must handle a particular number of simultaneous users or respond to requests within a certain timeframe.

While business objectives are critical to project success, they are generally captured as functional requirements, which detail the specific capabilities of the system. Detailed implementation tasks are more oriented towards the technical aspects of how to build a system rather than its operational characteristics. User interface elements relate specifically to the design and user experience aspect of the system, which again, falls outside the broader characteristics examined by non-functional requirements. Therefore, the focus on system behavior under different conditions distinctly characterizes non-functional requirements.