If you think of functional requirements as those that define what a system is supposed to do, non functional requirements (NFRs) define constraints which affect how the system should do it.. Nonfunctional requirements can be classified based on the user’s need for software quality. (b) Non-Functional Requirements List and briefly describe the main non-functional requirements for the LAABS. • -ilities : understandability, usability, modifiability, inter- If you can not measure it, you can not improve it.1  Lord Kelvin (1824 - 1907) 3 SEG3101 … July 1, 2016. admin. Respondents are often eager to provide a wish list of desired features for an interface design. The answer is usability. The definition of non-functional requirements is quality attributes that describe ways your product should behave. Non-functional requirements define system behaviour, features, and general characteristics that affect the user experience. I am writing a system requirements document and need to include non-functional requirements relating to the usability of the system, but am not sure of the best way to express this. Non-functional requirements examples. What is a non-functional requirement? Non-Functional Requirements SEG3101 (Fall 2010) 2 SEG3101 (Fall 2010). What is a Non-Functional Requirement? NON-FUNCTIONAL TESTING is defined as a type of Software testing to check non-functional aspects (performance, usability, reliability, etc) of a software application. While a system can still work if NFRs are not met, it may not meet user or stakeholder expectations, or the needs of the business. The resulting list becomes your Functional Requirements. The list of basic non-functional requirements includes: Usability Non-functional testing of Software involves testing the Software from the requirements which are non functional in nature related but important a well such as performance, security, user interface etc. “non functional requirement –generally informally stated, often contradictory, difficult to enforce during development and evaluate for the customer prior to delivery” Lawrence Chung What are Non-Functional Requirements? A usability requirement specifies how easy the system must be to use. 2. Usability is a non-functional requirement, because in its essence it doesn't specify parts of the system functionality, only how that functionality is to be perceived by the user, for instance how easy it must be to learn and how efficient it must be for carrying out user tasks. Usability requirements: The system must be able to be used on mobile phones as an application for easy use. Addressing a user concern will necessitate the formulation of a number of functional requirements, but the user concerns will also act to constrain other requirements that are characteristic of nonfunctional requirements. It is designed to test the readiness of a system as per nonfunctional parameters which are never addressed by functional testing. The system must be available at any time of the day for customers to book flights and for TEO Hong to check on any details for the bookings or the system. How well non-functional requirements are defined and executed determines how easy the system is to use, and is used to judge system performance. "The system shall be easy to use" seems a bit vague to me, and not testable. Non-functional Requirements capture conditions that do not directly relate to the behaviour or functionality of the solution, but rather describe environmental conditions under which the solution must remain effective or qualities that the systems must have.