Business requirement, Functionality requirements and Non-functionality requirements: Their differences, relationship and interdependence

Error and failure are what's left when we think everything else has been accounted for. Analyzing a business, an analyst needs to fully understand that there is a fine line between these three business concepts, their differences, relationship and interdependence, they need to be understood else confusing them together can lead to business failure in the short, medium and long run.

Business Requirements: A business requirement is not just something a system must do. It is something that the business needs to do or have in order to stay in business, take for example a business needs to increase sales, else, it'll run out of business, this a business requirement. It has to be done if not the business may not function properly or wind up for good . A business requirement is often less dynamic; it doesn't change often.

Functionality Requirements: A functional requirement describes how we perform our business processes (or their functionality), how a business intends to achieve its business requirements, a workflow diagram is a typical example of a Functionality requirements. It describes how the business would achieve it requirements. A company that knows that if it doesn't increase its business sales it'll run out of business, broadly speaking, Functionality requirements will talk about, how do we increase sales. The word "shall" is often the action word used in writing functionality requirements for a business, for example, Every customer shall receive a thank you email, after every purchase they make, to stimulate their continuous patronage, is a type of Functionality requirements.

Non-functionality requirements: Prolly the most crucial requirements but definitely the most neglected one. As opposed to process, this deals with the performance, capacity, speed, range of the Functionality requirements, for example, user experience. It's the property of a business process or product, while Functionality requirements are the features. Proffering a solution to a business, without incorporating the crucial Non-functionality requirements, the business solution might fail in the long run. For example, a business has agreed on sending Thank you mail to customers, but what happens when there's a lot traffic on the site, will the system be able to accommodate such traffic? Let's say the company sells umbrellas, what during the raining season when sales and demands are higher. This means that when creating a system software to send these automated emails, the likelihood and possibility of being overrun by demands and sales during the raining season should be factored in.

In summary, Business requirements states the "Why" for a business and its usually akin to business objectives and goals, Functionality requirements states the "what" and it's usually action related, more detailed and specific. Finally, the Non-functionality requirements states the "How well" and its usually related to testing and examination of business processes, actions taken, products and services.