If there is any one thing any project must have in order not to be doomed to failure, that is a sensible and comprehensive collection of both the functional and non-functional requirements. Any project’s requirements need to be well thought out, balanced and clearly understood by all involved, but perhaps of most importance is that they are not dropped or compromised halfway through the project. However, what exactly is the difference between ‘functional’ and ‘non functional’ requirements? It’s not that complex, and once you understand the difference, the definition will be clear. The official definition of ‘a functional requirement’ is that it essentially specifies something the system should do. Typically, functional requirements will specify a behaviour or function, for example: “Display the name, total size, available space and format of a flash drive connected to the USB port.” Other examples are “add customer” and “print invoice”. Some of the more t...