Functional and non-functional requirements

A functional requirement is something the product needs to work, perform an action and fulfill the purpose. It answers the question of “What does it do?”. They describe the minimal requirements of the product functionality. A non-funtional requirement is something that the product have to increase it quality. It answers the question of  “How does it do it?”. Non-functional requirements are extras made to improve the functionality of the product.

To be more precise, in software engineer, functional requirements define the functions of the system, is the description of the feature required. It also includes description of the required functions. Some examples of functional requirements are calculations, technical details, data manipulation and processing.

Non-Functional requirements focus on quality factors and effectiveness. These factors are what give value to the software and make the functional requirements function appropriately.


Some non-functional requirements may be:
1. Usability
2. Availability
3. Reliability
4. Flexibility
5. Supportability
6. Performance

References: (2016). Functional and Non-Functional Requirements. [online] Available at: [Accessed 13 Sep. 2016].

SearchSoftwareQuality. (2016). Functional vs non-functional requirements, what is the difference?. [online] Available at: [Accessed 13 Sep. 2016].

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