What are functional and non functional requirements ?

What are functional and non functional requirements in software engineering?

Functional and non Functional Requirements
Functional and non Functional Requirements

Functional requirements are the specific tasks, constraints, and goals that a software must meet in order to be considered complete. Non-functional requirements are any conditions or attributes of the software that do not directly impact its functionality, such as layout design or user experience.

Both types of requirements must be considered when developing a software project. Failure to meet either type of requirement can lead to major issues with the overall quality of the finished product.

Functional requirements can be broken down into six main categories:

1. User Interface

User interfaces should be easy to use and provide all necessary information needed by the end user. Additionally, they should be interactive and allow for flexibility and customization based on individual users’ needs.

2. Data storage and retrieval

Software should be able to store and retrieve data in an efficient manner, without causing any compatibility issues or data loss.

3. Performance

The software should perform satisfactory under normal operating conditions and should not overload the system or cause uncontrollable crashes.

4. Error Handling

Software must be able to handle any possible error condition without impacting the user’s experience or data integrity.

5. Cross-platform Compatibility

The software should work similarly on different platforms, including both desktop and mobile devices.

6. Testability

The software should be easily testable so that it can be verified for bugs and issues before it is released to the public.

Non Functional Requirements (NFRs) are a set of specifications that reflect the needs of the end user but are not necessarily related to the functionality of software. They might be related to user experience, data integrity, or interface design.

Non functionalrequirements tend to be more time consuming to write and test, so they should be specified in a way that minimizes the impact on the codebase. This might include separating out NFRs into separate functionality chunks, specifying impact level required for each NFR, and using automated testing tools to verify that all required NFRs are satisfied.

Below articles also help you to understand about types of requirements, Functional and non functional Requirements.  

  1. Functional Requirements: Best Practices for Writing Functional Requirements
  2. What are the types of requirements in software engineering
  3. What are nonfunctional requirements in software development


What is functional and non-functional requirements with examples?

There is non-functional testing such as usability, performance, stress, security, etc. Examples of the functional requirements are – Authentication of a user on trying to log in to the system. Examples of the non-functional requirements are – The background color of the screens should be light blue.

What are functional and non-functional requirements in software engineering tutorial point?

A functional requirement defines a system or its component. A nonfunctional requirement defines the quality attribute of a software system. It specifies “What should the software system do?” It places constraints on “How should the software system fulfill the functional requirements?

What are the 4 types of non-functional requirements?

What are non-functional requirements?

  • Nonfunctional requirements or NFRs are a set of specifications that describe the system’s operation capabilities and constraints and attempt to improve its functionality. …
  • Performance and scalability. …
  • Portability and compatibility. …
  • Reliability, maintainability, availability.

What is the difference between functional and non-functional?

And the main difference between functional and non functional requirements is that functional requirements describe what the system should do. On the other hand, non functional requirements describe how the system should perform.

What is a functional requirement example?

Functional requirements examples

The system must send a confirmation email whenever an order is placed. The system must allow blog visitors to sign up for the newsletter by leaving their email. The system must allow users to verify their accounts using their phone number.

What are two types of functional requirements?

Types of Functional Requirements

Here are the most common functional requirement types: Business Regulations. Certification Requirements. Reporting Requirements.

What are the 4 types of requirements?

The main types of requirements are:

  • Functional Requirements.
  • Performance Requirements.
  • System Technical Requirements.
  • Specifications.
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Author: Pallavi

Business Analyst , Functional Consultant, Provide Training on Business Analysis and SDLC Methodologies.

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