Mobile Apps | Requirements

Functional and Non-Functional Requirements for Mobile App: What’s the Difference?
Lvivity Team | February 20, 2021

Functional requirements for mobile applications describe what specifically needs to be implemented in a particular system or product and what actions users have to take to interact with the software. They determine what the system should do.

Non-functional requirements for mobile app show what properties and features a particular solution has, namely, how the system will work and why.

What do Functional Requirements Include?
We can highlight three main groups of functional requirements:
Business requirements. These define the high-level goals set by the customer’s company that is ordering the software development and stipulate what the system is to solve in terms of their business. Example: an application allowing potential customers to browse through the company’s product catalog and to purchase products.
User requirements. These describe the system goals/objectives the users may reach when using the created system (UseCases). Simply put, this is what a user can do: sign up, view certain content, recalculate data using a specific algorithm, and other functions.
Functional requirements. These define a list of actions the system has to perform. In addition, they have to specify how the system responds to various input data, how it behaves in particular situations, and so on.
This group also includes system requirements describing hardware and software environment features necessary for correct operation.

Non-Functional Requirements in Simple Words

As a rule, the non-functional requirements primarily include various product quality attributes determining system quality features, most often as examples below:
Availability – requirements for app continuous running, for example, 24/7, minimum idle time, etc.
Reliability – app behavior in case of alarm status, for example, automatic restart and operation recovery.
Scalability – ways to expand the system and avoid adversely affected performance.
Performance – how many simultaneous users or transactions the system is to service and its response time.
Security – app operation and use of safety requirements related to access control, private data processing, and external attack risk reduction.
Usability – ease of use and user-friendly interface, that allow users to seamlessly interact with the product.
Extensibility – requirements for app extensibility in case there is a need to add new functional requirements.

Wikipedia = Non-functional requirement


Author = Lvivity Team


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