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.

What are nonfunctional requirements in software development

What are Nonfunctional Requirements
What are Nonfunctional Requirements

Nonfunctional requirements (NFRs) are a type of requirement that falls outside of the functionality of a software system. They are typically requirements that are not related to user interaction or system functionality, and instead focus on aspects such as documentation, testing, or quality assurance. NFRs can be divided into two categories: reflectivity and nondiscrimination. Reflectivity refers to the need for a software system to maintain some level of consistency across different implementations. NFRs that affect consistency are sometimes referred to as “contract statements”. Nondiscrimination refers to the need for a software system to be able to handle different inputs and outputs in an equitable way. For example, one requirement might be for a software system to print in both inches and centimeters.

Nonfunctional requirements are usually overlooked during software development, but they are definitely crucial for the success of a project. Capture the nonfunctional requirements in your project early on to ensure that the project is successful. Here are some tips for capturing nonfunctional requirements:

When defining scope, be concise and accurate. Too much detail will cause confusion and delays in the project. This is especially important when dealing with nonfunctional requirements because they can often change during the development process. By keeping scope concise and accurate, you will avoid any potential problems down the line.

2. Clarify customer expectations upfront

Before beginning development, it is helpful to clarify customer expectations upfront. This way, both you and the customer know what to expect from the project and there are no surprises later on. It also prevents misunderstandings and arguments that could lead to delays in the project.

3. Obtain feedback frequently

It is important to obtain feedback frequently throughout the development process. This way, you can identify any changes or updates that need to be made to the scope or specifications. Feedback from both your team and customers will help ensure a successful product launch.

Tips to capture the nonfunctional requirements in software development

Software development is a complex and challenging process, but it’s not all the glamorous work. There are some nonfunctional requirements (NFRs) that are just as important, if not more so, than the functional requirements.

If you want your software to be reliable, efficient, and secure, you need to pay attention to NFRs. Here are five tips for capturing NFRs in your development process:

1. Define and track deadlines. Establish target completion dates for each stage of the product development cycle, and make sure everyone understands them. This way, everyone knows what their responsibilities are and when they need to start working on a particular area.

2. Communicate frequently. Keep everyone updated on the project’s status—both informally and through formal statements and reports—and avoid silos where different groups have limited or no knowledge of the overall progress of the product. This communication will help build trust and ensure that everyone is working towards the same goal.

3. Encourage creativity and innovation. Give employees room to try new approaches and think outside the box; this will help them come up with innovative solutions to problems as well as make better use of existing resources.

4. Ensure traceability back to Requirements Management Documents (RMDs). All changes made during the development process should be documented in RMDs so that you can track progress back to original requirements documents (or at least earlier versions thereof). If there’s any ambiguity about how a particular requirement should be implemented, go back to the RMD and reconsider your approach.

5. Celebrate successes! Praise workers when they deliver on time or meet other tangible success criteria; acknowledgment breeds motivation!

You can go through the below articles also.

10 Requirement Gathering Techniques to Kickstart Project


What are non-functional requirements?

Nonfunctional Requirements (NFRs) define system attributes such as security, reliability, performance, maintainability, scalability, and usability. They serve as constraints or restrictions on the design of the system across the different backlog

What are non-functional requirements examples?

Here are nine examples of nonfunctional requirements and their significance to applications:
Speed. Speed determines how fast an application responds to commands. …
Security. …
Portability. …
Compatibility. …
Capacity. …
Reliability. …
Environment. …

What are three types of non-functional requirements?

Types of Non-functional Requirement : ScalabilityReliabilityRegulatory.

What are functional and no functional requirements?

A functional requirement defines a system or its component. A non-functional requirement defines the quality attribute of a software system. It specifies “What should the software system do?

What are non functional test requirements?

Non functional requirements includes the maintenance testing, Documentation testing which are not required while execution is going on but one the application has gone live. It is known as functional requirement only. Also known as Quality requirements.

What is Requirement in software engineering?


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