What is included in functional requirements for software?

Functional requirements define the specific behavior, functions, and capabilities that a software system must provide. They detail what the system should do, describing interactions between the system and its users or other systems. By focusing on the expected outputs and how they relate to various inputs and user actions, functional requirements ensure that the system meets the necessary obligations for performance and user satisfaction. This includes specifications such as user authentication, data processing, calculations, and any other interactions that the software is expected to manage.

While system architecture, user interface design, and hardware requirements are important aspects of software development, they fall under different categories. System architecture relates to the overall design of the system's structure, user interface design involves how users will interact with the software, and hardware requirements specify the physical equipment needed to run the software. These elements support the functional requirements but do not define the core behaviors and functionalities of the software itself. Hence, the emphasis on behavior or function specifications accurately captures the essence of what functional requirements entail.