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Functional requirements vs Non-functional requirements: differences and examples

Functional requirements vs Non-functional requirements: differences and examples

August 30, 2022
->
8 min read
Business
By
Simon Shcherbak
Business Analyst

Imagine you are preparing a holiday feast. Whatever the occasion, cooking meals, crafting cozy decor, and preparing garden zones are quite challenging tasks. How many guests? Photographer? What will be on the menu? 🤔

It's the same story when building apps. Designing UI, creating effective architecture, and delivering the necessary functionality is a kind of software development fine art.

Here's where requirements matter: functional and non-functional, they play a vital role in the software development process. Let's explore the reasons why.

What are functional requirements?

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

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

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

Let's break down these two.

Functional requirements define actions the product must provide to benefit users. Simply put, they describe:

what your product must do — its operations and workflows
business logic that meet user needs
way the product will fulfill regulatory compliance and standards

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

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

examples of functions

Software requirements (functional and non-functional) are crafted by business analysts together with the development team, including software engineers, solution architects, and other IT specialists. Collaboration among stakeholders is crucial to ensure that all requirements accurately meet both users and business needs.

What is a non-functional requirement?

While a functional requirements specification is a kind of guide to the functions or tasks of the product, non-functional requirements (NFR) outline <medium>quality attributes<medium> designed to improve the product's functionality and user experience.

examples of non functions

There are multiple -itys that serve as pillars for a good user experience. Defining them in advance provides you with a handy checklist to ensure you capture all critical requirements for the future product.

1
Usability
2
Capacity, Performance, and Scalability
3
Data Integrity and Interoperability
4
Security
5
Reliability, Maintainability, and Recoverability

If you want to expand your software product while your business grows, saying 'product must be scalable' is not enough.

You have to be specific. For example, you can 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 a vague project scope and mismatches between the project plan, client expectations, timeframes, and budget.

Freshcode Tip
Remember that realizing 100% of each non-functional requirement's potential isn't possible; for instance, the security requirement can conflict with usability or availability. This is why it's so important to prioritize each requirement and identify the most crucial of them.

Difference between functional and non-functional requirements

difference between func and non-func

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

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

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

Therefore, only the yin-yang combination of functional and 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 business analysis map and show why each stage is non-skippable in app development.

Business analysts are responsible for creating proper software requirements, both functional and non-functional. It requires careful preparation and a strong grasp of both technology and the market.

Writing software requirements is a complex task that brings important insights and practical outcomes. The process involves multiple stages, from initial meetings and discussions with stakeholders to structuring all the data into comprehensive requirements documentation.

1
Project Vision Document (PVD)
The Project Vision Document outlines a compelling concept for the software development project, specifying the product or service to be developed in alignment with the client's business needs, product mission, and desired functionality.
2
Requirement Management Plan (RMP)
The RMP is designed to set up the procedures for collecting and managing project requirements. It describes how you will gather, analyze, document and manage them. The main purpose of requirements management plan is to ensure product development goals are successfully met.
3
Software Requirements Specification (SRS, SRD)
Software Requirements Specification is a document that provides a detailed description of what a software product is expected to do, its functionalities, constraints, performance, user interactions, and other attributes. It is a foundation for building software that meets stakeholders' needs and expectations.
Freshcode Tip
You can find detailed info on how to create a perfect SRS in our article: Software Requirements Document: How To Create | Tips From Developers

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

During requirements management, business analysts produce various artifacts to document and organize the software requirements effectively. Below, you can find more details about them.

To-do list
1
Title
small smile positive red
Project Background
small smile positive red
Project Vision
small smile positive red
Business Requirements
2
Investigate end-users needs
small smile positive red
User Roles
small smile positive red
User Requirements
3
Design UX system according to user requirements
small smile positive red
Wireframes
4
Prepare operational documentation
small smile positive red
Functional and Non-Functional Requirements
small smile negative red
TextTextTextTextTextTextTextTextTextText
5
Architecture Diagram
small smile positive red
Сhoose the right architecture for the software
6
Estimate resource costs for the project
small smile positive red
Work Breakdown Structure
7
Prioritize product features
small smile positive red
Software Development Plan
small smile positive red
Development Time Frame
Want to know more about key business analysis documentation to start your project?
Contact our team

How do we work with project requirements at Freshcode?

After years of analyzing and implementing various techniques and approaches, we have significantly simplified our requirement engineering process without compromising quality.

By deep understanding the needs of clients and users and creating a clear picture of the software product, we can find the strengths and weaknesses of each solution. Finally, after reaching an agreement with the client, the best possible solution is implemented. Our approach saves time and costs for both parties, preventing cases when work goes down the drain.

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

Software Requirements Gathering

A good business idea is a great start. From our side, we assist businesses in strengthening their projects with the best approaches, leveraging our technology expertise and experience in different business domains.

Our team is always ready to discuss a tech-savvy business strategy that aligns your business case. If you wish to learn more about Freshcode's expertise, our product delivery process, or get an initial project estimation, please contact us for a free consultation and a warm welcome 🙂

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

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Author
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Simon Shcherbak
Business Analyst

With six years at Freshcode, Simon adeptly transforms business needs into clear technical solutions. He partners with stakeholders to ensure IT projects meet strategic objectives.

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