Functional requirements vs Non-functional requirements: differences & examples

What are functional requirements?

According to Statista, the main reasons why startups failed are running out of funds (38%), and lack of market need (35%). Flawed business models and skills mismatch were named among other pitfalls ⛔️

Many of these issues can be caused by one seemingly indirect thing — poorly written <medium>product requirements<medium>. Carefully designed and well-documented, they are essential to any project.

In the technology world, requirements are generally categorized into two types: <medium>functional and non-functional<medium>. They form a clear vision of the future product and serve as a roadmap for the development team. Both of them define <medium>desired system behavior<medium>, but the different sides of the last.

Let's break down these two.

<medium>Functional requirements<medium> define actions the product must provide in order to benefit users. Simply put, they describe:

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These requirements are determined by the <medium>business needs and task analysis<medium>. They can be documented and described through the use cases.

To start with simple functional requirements examples, let's look at the... coffee cup.

Software requirements (both functional and non-functional) are crafted by business analysts, in consultation with the development team, including software engineers, solution architects, and other IT specialists.

What is a non-functional requirement?

While functional requirements specification is a kind of guide to the product's underhood and a statement of how it must behave, non-functional requirements (NFR) specify <medium>quality attributes<medium> designed to <medium>improve the product's functionality and user experience.<medium>

They are various "itys" , serving as pillars for the <medium>solid vault of good user experience<medium>. Defining them upfront provides a handy checklist to ensure you don't miss critical requirements for the future product.

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If you want to expand your software product along with your business, saying "product must be scalable" <medium>is not enough.<medium>

You need to be specific, so you might define this point as "develop a system that can manage at least 100,000 users over the next 24 months, so customers don't experience app crashes and errors".

A lack of prioritized non-function requirements can result in vague project scope and a disconnect between the project plan, client expectations, timeframes, and budget.

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Difference between functional and non functional requirements

If functional requirements define the product's key tasks (what does it have to do), non-functional requirements determine the way it should be done (how does it have to do it). Their key difference is that the first ones are vital for the system; without meeting them, your product simply won't work.

Non-functions, in turn, focus on a user experience; the system will work without them. The other thing is that it will lose its meaning — who'd buy a guitar with a bad finish, strings that break too quickly, and no strap button? You can play such an instrument, but <medium>Gibson Les Paul will always outperform your product.<medium>

So, don't take this in a way that working on non-functional requirements is less significant. Remember that <medium>user-centered design<medium> rocks: unless the app is user-friendly, your project will not succeed just as well.

Therefore, only the yin-yang combination of functional vs non-functional requirements matters — one cannot exist without the other ️️

How to write functional vs non-functional requirements?

Here I want to guide you through the key points on the BA's map and show why all of them are non-skippable stages of app development.

Business analysts are responsible for creating requirements, both functional and non-functional. This <medium>process includes different stages<medium>, from calls and discussions with stakeholders, discovering their pain points, needs, and expectations, to designing all the data into structured requirements documentation.

This documentation supports the decision-making process, builds a strong background for further product development, and speeds up time-to-market.

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Creating software requirements is a complex task that includes a set of processes. And most importantly, it brings critical insights and practical outcomes.

Full-fledged SRD requires careful preparation and solid knowledge of both technology and the market. Below you can find what artifacts are produced during requirements management handled by business analysts.

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How do we work with requirements at Freshcode?

After years of analyzing and implementing various techniques and approaches, we maximally <medium>simplified our requirement engineering process without loss of quality.<medium>

By puzzling clients' and users' needs and creating a clear picture of the future software product, we find the strengths and weaknesses of each solution. Agreed with the client, the best possible is chosen. Thus, both sides save time and costs,<medium> preventing cases when hard work is going down the drain.<medium>

Here is a <medium>brief step-by-step guide<medium> on how we process product requirements, from the initial discussion to the final documentation:

A good business idea is a great start. We just assist businesses to strengthen their projects with the best approaches, <medium>including software requirements engineering.<medium>

Our team is always ready to talk about tech-savvy business strategies through the prism of software development. If you want to know more about Freshcode's <medium>expertise, product delivery process, or get a project estimation<medium> — we offer you a free consultation and a warm welcome.

Also, you can contact our COO on Linkedin to get info about Freshcode solutions.