Understanding Functional And Non-Functional Requirements

14th Oct 2021

When developing software and applications, functional and non-functional requirements shape the features found in the end product.

Approaching a project in terms of defining these two sets of requirements is an excellent way to encourage transparency across a project, ensuring developers and their clients meet agreed goals. This approach also mitigates the risk of communication errors during development.

Understanding the differences between functional and non-functional requirements is therefore important in ensuring the success of software development.

What Is A Functional Requirement?

A functional requirement is a term used in software development to outline the functions of an application or component within a piece of software.

In effect, functional requirements are the essence of a piece of software, outlining its overall functionality: the tasks it will perform, the data it will use and the processes.

Functional requirements can be broken into three stages:

• Data input
• System behaviour
• Data output

Importance Of Functional Requirements

Functional requirements are important because they outline the overall functionality of a piece of software in a way that developers and customers are both agreed upon.

They also offer useful milestones in the development roadmap that can help guide developers towards the agreed-upon end goal.

What Is A Non-Functional Requirement?

A non-functional requirement looks at performance and the overall effectiveness of the software or application.

Where a functional requirement is more concerned with what a piece of software does, non-functional requirements look at how the system achieves the product’s aims. They are also used to assess the effectiveness, security, scalability and usability of the solution.

Importance of Non-Functional Requirements

A non-functional requirement might not be essential, but it can futureproof software, make it usable in specific environments and make it easier to scale up or down if necessary.

If a piece of software lacks some of its intended non-functional requirements, it will still operate as intended. However, it risks having bugs, running poorly or lacking optimisation.

Non-functional requirements are also important as they help developers outline the abilities and limits of their solution. This makes for better software development because it is more precise in terms of scope. Moreover, non-functional requirements add polish to an application or piece of software, making it feel more complete.

TechReach is an outsourced software developer. We align our development processes to include functional and non-functional requirements within our project.

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