Non-Functional Requirements (NFRs) refer to the criteria that define how a system performs its functions rather than what functions it performs. They encompass aspects such as performance, security, usability, and reliability. NFRs help ensure that a system meets user expectations and operates effectively under various conditions. These requirements are crucial for the overall quality of a system. For instance, a software application may need to load within two seconds (performance) or maintain data privacy (security). By addressing NFRs, developers can create systems that not only work correctly but also provide a satisfactory user experience.