The Functional Requirements Document (FRD) is a formal statement of an application’s functional requirements. When clearly defined, requirements lead to successful project outcomes. Approved requirements establish an agreement between the customer (internal or external) and a provider to reach the same goal. In this article, we explain the need for a functional requirements document, its structure, contents, and offer a sample template format for your work.
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An FRD or Functional Requirements Document serves as a contract for formal statement, between the business stakeholders and the technology team, on an application’s functional requirements. The FRD is produced by business analysts or sometimes the technical team in response to the business requirements (captured in a BRD – Business Requirements Document).
The key purpose of an FRD is to translate business needs into technological functions in a system. It’s where project stakeholders and the technical development team meet. The creation of the FRD facilitates and ensures collaboration between business and technical stakeholders:
While created by the solution team comprising business analysts, the FRD should be solution independent (in general) and it should express what the application should do and not how it should do it. The FRD should not commit the technical team to a specific design. It is for the technical team to develop the actual design and implementation tactics.
The Functional Requirements Document (FRD) is one of the most popular ways to express functional specifications and define the requirements and functional solutions.
Click the button to download the example FRD template format for your work.
The Business Analysis Body of Knowledge (BABOK) acknowledges requirements as a usable representation of a need. Unambiguous, and detailed requirements help reduce cost and schedule risks and keeps the project on track.
The following are some uncategorized examples of software requirements:
While the list of requirements above may suffice on smaller projects, large software development needs a more steady and structured approach. The FRD is a derivative and expanded version of the business requirement document BRD.
Functional requirements capture the intended behavior of the system and hence are tailored to fit the project’s need. This behavior may be expressed as services, tasks or functions the system is required to perform. The functional requirements are designed for the readership of a general audience to understand the system. Business as well as technical stakeholders should comprehend the same details in the FRD. Hence, no technical knowledge is required to understand this document.
The Functional Requirements Document (FRD) serves the following purpose:
Click the button to download the example FRD template format for your work.
Functional requirements are classified in a variety of ways. Commonly these are broken down in to functions as such:
Both functional and nonfunctional requirements can be formalized in the Functional Requirements Document. FRD / FRS’s contain descriptions of features, functions and abilities that the software product must provide. The document also defines constraints and assumptions. These can be a single document communicating functional requirements or it may accompany other software documentation like user stories and use cases.
The FRD is created for the entire solution or a part of it, and is usually an iterative process of consultations with business and technical stakeholders. Every feature must be documented before actually developing it. It is not uncommon for the FRD to undergo a series of revisions as the product is developed over multiple releases. This is because as newer information and client feedback is received, the development team gains greater clarity of the objectives. Everyone understands the importance of features, which can be accordingly prioritized.
The FRD / FRS includes all or part of the following sections:
This list of sections is meant to be representative and a guide, not a hard and fast rule. Every project is different, and you will need to determine the level of detail required for your FRD. For free support with your FRD, use the chat box to chat with our support team or send an email to support@savioglobal.com.
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Click the button to download the example FRD template format for your work.
Use cases describe the interaction between the system and external users that leads to achieving particular goals.
Each use case includes three main elements:
There are two formats to represent use cases:
A use case specification represents the sequence of events along with other information that relates to this use case. A typical use case specification template includes the following information:
A use case diagram doesn’t contain a lot of details. It shows a high-level overview of the relationships between actors, different use cases, and the system.
The use case diagram includes the following main elements:
Example:
The Agile Alliance describes user stories as work that is divided up into functional increments. User stories are developed and represented in a format that emphasizes the value to the end user of the system. A typical user story describes three components:
User stories are modelled on the following lines:
Functional requirements are product features or functions that developers must implement to enable users to accomplish their tasks. So, it’s important to make them clear both for the development team and the stakeholders. Generally, functional requirements describe system behavior under specific conditions. For example, the system should:
Nonfunctional requirements define how the system should perform. Some examples are:
Here’s a brief comparison and then we’ll proceed to a more in-depth explanation of each group.
| Parameter | Functional requirements | Nonfunctional requirements |
|---|---|---|
| Objective | Describe what the product does | Describe how the product works |
| End result | Define product features | Define product properties |
| Focus | User requirements | User expectations |
| Documentation | Captured in use case | Captured as a quality attribute |
| Essentiality | They are mandatory | They are not mandatory, but desirable |
| Origin type | Usually user defined | Usually developer defined or other tech experts |
| Testing Precedence | Tested before nonfunctional testing | Tested after functional testing. |
| Examples | – User interface, – authentication, – authorization levels, – business rules, etc. | – Performance, – usability, – security – testing, etc. |
Click the button to download the example FRD template format for your work.
Nonfunctional requirements describe how a system must behave and establish constraints of its functionality. The following are the most typical nonfunctional requirements utilized in most functional requirements documents FRD.
Usability defines how difficult it will be for a user to learn and operate the system. Here’s how usability can be evaluated:
Example: Usability requirements can consider language barriers and localization tasks: People with no understanding of French must be able to use the product. Or you may set accessibility requirements: Keyboard users who navigate a website using , must be able to reach the “Add to cart” button from a product page within 15 clicks.
Security requirements ensure that the software is protected from unauthorized access to the system and its stored data. It considers different levels of authorization and authentication across different users roles. For instance, data privacy is a security characteristic that describes who can create, see, copy, change, or delete information. Security also includes protection against viruses and malware attacks.
Example: Access permissions for the particular system information may only be changed by the system’s data administrator.
Reliability defines how likely it is for the software to work without failure for a given period of time. It decreases because of bugs in the code, hardware failures, or problems with other system components. To measure software reliability, you can count the percentage of operations that are completed correctly or track the average period of time the system runs before failing.
Example: The database update process must roll back all related updates when any update fails.
Performance is a quality attribute that describes the responsiveness of the system to various user interactions with it. Poor performance leads to negative user experience. It also jeopardizes system safety when it’s overloaded.
Example: The front-page load time must be no more than 2 seconds for users that access the website using an LTE mobile connection.
Availability is gauged in terms of time that the system’s functionality and services are available for use with all operations. So, scheduled maintenance periods directly influence this parameter. And it’s important to define how the impact of maintenance can be minimized. When writing the availability requirements, the team has to define the most critical components of the system that must be available at all times. You should also prepare user notifications in case the system or one of its parts becomes unavailable.
Example: New module deployment mustn’t impact front page, product pages, and check out pages availability and mustn’t take longer than one hour. The rest of the pages that may experience problems must display a notification with a timer showing when the system is going to be up again.
Scalability requirements describe how the system must grow without negative influence on its performance. This means serving more users, processing more data, and doing more transactions. Scalability has both hardware and software implications. For instance, you can add memory, servers, or disk space to increase scalability. On the other hand, you can compress data, use optimizing algorithms, etc.
Example: The website attendance limit must be scalable enough to support 200,000 users at a time.
Click the button to download the example FRD template format for your work.
Prototypes are meant to be inexpensive and quickly developed visual representations of requirements. Wireframes are low-detail illustrations of a website or an app. To break it down, wireframes are low-fidelity, basic layout and structural guidelines of your web product’s layout and prototypes are an advanced wireframe with more visual detail and interaction.
Wireframes serve as the foundation of a website or app’s visual layout, and it is at this stage that you will arrange elements on the page or screen. The purpose is to map out the priority of the content on the screen. A good rule of thumb is to keep your wireframes simple, with details that represent the core structure of your site / app only.
Creating documentation is an integral part of any software development project. Well-documented requirements ensure that stakeholders and developers are on the same page and also help define project scope and budget. Here are a few useful tips on how to make great documentation.
Requirements have to be clear and understandable. Make sure your requirements are stated in a concise manner that doesn’t contain ambiguity or allow different interpretations. Also, try to avoid technological jargon. Remember that each audience is different and stakeholders might not be familiar with specialized tech terminology. Instead, enrich your documents with visuals, diagrams, and graphs to support the information and make it easier to perceive. Adding glossaries and cross-links is also helpful.
Requirements have to be specific, accurate, and complete. When writing your documentation, be consistent with the language and make sure that your requirements are accurate. They should cover every scenario, but never contradict each other. Avoid vagueness and weak phrases such as “system has to be fast” or “when something happens.” Be specific and quantify the terms so that all the readers can understand them in the same way.
Requirements have to be testable. Write requirements in such a way that after the product is created, testing can show whether they are delivered successfully. The FRD is frequently used as a bases for user acceptance test case development and testing.
Requirements have to be feasible and sensible. Focus on the functionality and quality attributes that users actually need. Remember that requirements have to reflect higher-level business objectives.
