In information technology (IT) and software engineering, functional requirements delineate the system as a whole or its particular components. They are product functions or features that must be implemented by developers to facilitate the user’s ability to execute their tasks. Functional requirements delineate a system’s behavior under a given condition. Therefore, it is crucial to elucidate the above-mentioned requisites for stakeholders and the development team. On the other hand, the nonfunctional requirements generally elucidate the attributes such as usability, scalability, maintainability, performance, reliability, and security of a specific system. They typically act as limits or constraints on a program’s design across various backlogs. Also identified as system qualities, the aforementioned prerequisites are as crucial as functional stories, features, capabilities, and epics.
Nonfunctional requirements play an instrumental role in enhancing the effectiveness and usability of the complete software system. Inadequacies in meeting any of the aforementioned requisites may result in a failure to fulfill market, user, or business needs and to conform to the mandatory stipulations imposed by standards or regulatory agencies. In contrast, a functional requirement helps the user comprehend the projected behavior of a specified software system. Regarding systems operations, the most typical nonfunctional requirement categories include data integrity, manageability, interoperability, availability, serviceability, usability, reliability, and scalability. Functional requirements comprise business regulations, audit tracking, authentication, certifications, transaction corrections, external interfaces, legal stipulations, authorization levels, and reporting preconditions.
Functional requirements are usually elucidated at a component level, whereas the non-functional prerequisites are applied to the entire system. Furthermore, functional specifications help one verify a software’s capabilities, while nonfunctional stipulations facilitate the validation of a program’s performance. Regarding a secure online shopping system, various functional and non-functional business requirements should be implemented to ensure the system’s proper functioning and efficiency. Examples of the nonfunctional business requirements include protecting customers private information while interacting with the system and the optimization of the online shopping platform to enhance its capacity to accommodate a large number of users (customers) without recording performance failures. Functional requirements on an e-shopping site incorporate user authentication upon their attempt to log in or access the system and system shutdown in the event of a suspected cyber-attack incidence.