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An Overview of Software Requirement Specification (SRS)


A software requirements specification (SRS) is a detailed description of a software system that will be formed. It is modelled after the specification of business requirements. The software requirements specification specifies functional and non-functional requirements, as well as a set of use cases that describe the user interactions that the software must provide for ideal interaction. SRS is generally made before going into designing part.

  • SRS in software engineering establishes the foundation for all documentation. If you don't have an SRS, your entire documentation will lack a consistent structure. You won't see the big picture of your project, and you'll end up with dozens of files that don't fit into a single framework.

  • Your communication is put on the right track with SRS. To create a thorough list of requirements, product owners, stakeholders, and developers must initially come to an understanding. Before a single line of code is written, misconceptions become clear when you talk about and explain SRS.

  • SRS assists you in understanding the product. Too often, the product owners and developers have differing viewpoints on the project. In the end, both parties are dissatisfied with the outcome. SRS assists in developing a common perspective on the project.

  • Your development standards improve when you have SRS documentation to refer to. Everyone involved in the project is aware of the product's scope and the standards that must be met.

  • Risks are alleviated. When you know what functionality, you're going to build, you can predict what might go wrong at each stage of development. This aids in the creation of an accurate budget and time estimates, as well as the early identification of risks.

All parties involved in software development can better understand their priorities with the help of a software specification requirements document. While stakeholders become familiar with the technology that the software engineering team uses, developers become familiar with the business objectives of a product owner. SRS unites technological and financial objectives while keeping everyone informed.

Structure of SRS Document

SRS programme documentation will serve as a team's ultimate manual for creating products. Before design and development, the team does not necessarily need to finish the entire document; you may return to it later.

Let's take a quick look at the things indicated in the image above.


The introduction explains the structure, scope, and overall significance of SRS for your team.

  • Purpose: Describe the structure and goal of the SRS software documentation in this section, including the kinds of requirements that will be covered and the users of the document. This section should be brief: 1-2 paragraphs should suffice.

  • Intended audience: You can go into detail about which stakeholders and teams will collaborate with SRS and participate in its development. These are typically product owners, investors, business analysts, developers, testers, and operations teams. The entire structure is determined by your software development methodology and the structure of your team.

  • Intended Use: Describe the circumstances in which your team will utilise the SRS. It's typically employed in the following situations:

  • Creating and generating ideas for new features;

  • Scheduling project time, sprints, and budgets;

  • Assessing risks;

  • Tracking and evaluating the team's performance;

  • Contradictory circumstances where parties involved have various ideas of what constitutes a well-executed project.

  • Scope: You must quickly define the system's main function, functionality, and location in this section because it describes the product's range of applications. Similar to how you would introduce a product at a stakeholder meeting, but with more in-depth technical information. All expected user categories must be described in this area, along with all key components of the architecture. The requirements documents must also clearly state how the solution under development differs from competing products and highlight the key tactics for revolutionising the market. Based on the complexity and scale of the software project, an SRS document's scope and detail may change. The Software Requirements Specification (SRS) is a key document that details the specifications and goals for the software and serves as a roadmap for the design and development process.

  • Definitions and acronyms: The team frequently uses particular terms in your text. The definition of these terms will help with the onboarding of new developers, the resolution of contradictory circumstances, and the elimination of any misconceptions. The functionality, applied technology, target audiences, business entities (users, clients, middlemen), and stakeholders are all described in the definitions. To write an SRS quicker, you might decide to use an acronym to refer to a specific user group. The document will be readable as long as you include it in the table of definitions.

Overall Description
  • User Needs: Some teams decide not to include this section in their SRS engineering documentation because it is unpredictable. We believe it's best to list the user issues your functionality is intended to address. You'll need it later on for functionality monitoring and brainstorming. You can refer back to this section at any time during the creation of your product to make sure the user experience team hasn't gone off course. Needs are problems that the system will be able to help people solve. If you work with a highly segmented audience, you can break demands down into subcategories. Avoid going into great depth about each user's wants. In case a problem turns out to be more important than you initially imagined, you need to give some space for interpretation.

  • Assumptions and dependencies: The team's ideas about the product and its functionality are referred to as assumptions, and they are generally accurate. For instance, it makes sense to expect that a platform that aids drivers in navigating at night will be used primarily in night mode. What makes assumptions crucial? They let you to concentrate initially on the core features of the app's operation. This presumption makes it easier to see why interface developers need to create a system that is compatible with vision in low light for a night-driving assistance. You don't need to include related features in the first iteration because it's doubtful that any users will open the app during the day.

System Requirements

These specifications are used to direct the design and development of the software and are crucial for ensuring that it will operate as intended in the specified environment. They are also used to pinpoint any potential restrictions or difficulties that might affect the software's deployment or implementation.

This section outlines product functionality and the standards for its execution. You'll find a more detailed description here because the first two sections only covered the product's essential features.

  • Functional Requirements: Functional requirements specify the essential functionality that must be provided, which is essential to the software project's success. In order to make sure that the software satisfies the needs and expectations of the user and stakeholders, they are utilised to direct the design and development process. For a software solution to meet the project's aims and objectives, precise and thorough functional requirements are crucial. Instead of answering the questions "How?" and "When?", these criteria address the issue "What will be developed?"

  • External Interface Requirements: For the software to efficiently connect and communicate with other systems and devices, external interface requirements are crucial. They supply the necessary data for system interfaces and aid in defining the software's parameters and constraints. The development team can guarantee that the software will be able to interact with the outside environment efficiently and satisfy the expectations of the user and stakeholders by precisely outlining these criteria. Some teams decide to categorise them to make the document easier to read. Typically, backend and business logic are not included in descriptions of SRS design components. This makes sense given that designers tackle this task more frequently than developers and that it also marks the beginning of the product development process.

External interface requirements can consist of four types:

  • User interface;

  • Software interface;

  • Hardware interface;

  • Communication interface.

The requirements for the external interface specify the page elements that the client will see (client-side of the application). They can consist of the page count, design components, significant stylistic motifs, or even creative components if they are crucial to the finished output.

  • System Requirements: The standards and limitations that describe the hardware, software, network, and other components necessary to efficiently operate the software system under development are referred to as system requirements in Software Requirements Specification (SRS). This can include technical details like the operating system, memory size, processor speed, storage capacity, and other elements that affect the functionality and performance of the software system. To make sure that the software system is appropriately conceived, produced, and deployed, developers, system administrators, and other stakeholders frequently employ SRS system requirements. Although it may seem difficult to create system requirements before beginning to construct a product, it is crucial. To avoid having to rework the project later, developers must adhere to the hardware standards they rely on. This is crucial for mobile apps and apps where responsiveness is valued highly (games, VR/AR products, Internet of Things, etc.).

  • Non-Functional Requirements: In a Software Requirements Specification (SRS), non-functional requirements are those desired characteristics and limitations of a software system that are not connected to particular functions or features of the system. Non-functional requirements define how, while functional requirements address the question of what to develop. These specifications list the characteristics of the system that must be met, including performance, security, usability, reliability, maintainability, and other factors. The system's desired degree of performance, response time, security, scalability, and other aspects are specified in non-functional criteria, which also serve as a framework for assessing how well the software system satisfies the expectations of its users. Response time, the maximum number of concurrent users, and data protection requirements are a few examples of non-functional requirements. These specifications aid in ensuring that the software system is appropriate for its intended use and satisfies the needs of its stakeholders.

Tools for SRS Documentation

You need to use a tool for information collection and organising in order to create software requirement documents that are clear and understandable. Fortunately, there are numerous useful frameworks that may be applied right away. Here are our primary tools for developing SRS and managing subsequent products.

Context Diagram / System Context Diagram

It is also known as Level 0 Data Flow Diagram. The context diagram assembles each part of the system into a comprehensive view. It pinpoints the information flows between the system and outside parties (i.e., actors). Requirements document frequently includes a context diagram. It must be written in plain language so that all project stakeholders may comprehend it because it must be read by all project stakeholders. A system context diagram is often used early in a project to determine the scope under investigation. A system context diagram represents all external entities that may interact with a system. A significant advantage of a context diagram is that it provides clear visual representation. Here is an example context diagram for a Sale Order System:

Functional Decomposition

A functional decomposition diagram includes the entire function or project as well as all required supporting tasks. From commerce and industry to computer programming and artificial intelligence, functional decomposition is a tool used to solve problems in many different contexts. This tool presents a hierarchic view of the system. You see which features are more important than the others and understand the dependencies in the project.

Use Case Diagram

Use case diagrams show how a live system behaves dynamically. It simulates how a third party interacts with the system to make it function. Use case diagrams are in charge of representing the outside elements that communicate with the component of the system. Following is an example of use case at airport:

Sequence Diagram

Functional requirements can use sequence diagrams to specify how a particular feature changes over time or in response to various user inputs. The diagram in this illustration shows the flow of an email notice. Any kind of feature or piece of data can be used with a tool like this.

AS-IS and TO-BE process model

An AS-IS to TO-BE process model is a graphic representation of a process's present state and its anticipated future state that shows the discrepancies and contrasts between the two. In business process improvement projects, where firms seek to find and eliminate inefficiencies, streamline processes, and enhance overall performance, this approach is frequently utilised. Applications, agents, and connected parties are all included in AS-IS models. In this way, the diagram offers a perspective on action-taking users, intermediaries, and final stakeholders. Additionally, links between different features or functionality and its inputs and outputs can be defined using it. Here is an example of an online shop that sells goods online. When a salesperson gets a customer's purchase order, they first check the stock level before starting the procedure. The salesperson will pack them if there is sufficient stock to fill the order. They are shipped off together with an invoice to complete the process. If there isn't enough inventory, the salesperson will advise the customer to modify the purchase order.

The TO-BE diagram demonstrates how your software can transform current procedures. It's useful since you can observe how the interactions are enhanced and where exactly the software is used in the process. The diagram makes it simple to follow and keep track of the progression of events.

User Stories

User Stories in Software Requirements Specification (SRS) are a simple and flexible way to describe the desired functionality of a software system from the perspective of the end user. They are short, concise statements that capture the essence of a user’s needs and requirements in a way that is easily understandable by both technical and non-technical stakeholders. A user story typically follows the format "As a [type of user], I want [some goal or feature], so that [some benefit or value is achieved]." User stories help to break down complex requirements into manageable and testable chunks, and provide a basis for further elaboration and analysis during the software development process.

Mind Maps

A mind map is a graphic representation of concepts and ideas. It is a sophisticated method of taking notes that uses words, lines, photos, symbols, colours, and shapes.

This makes it easier to structure information, which improves your understanding of the requirements. It also makes it easier to evaluate and cover the material thoroughly.

When there are so many established techniques available, why do we need a mind map? What distinguishes this from concept maps?

  • Increases imagination

  • It's simple to put the concept into creative practise.

  • Mind Maps are very adaptable and simple to maintain.

  • More ground is covered.

  • May centralise all the data so that you don't always have to switch between sites.

  • The management can express it without difficulty or complication.

  • To make certain locations more appealing, we might designate them in various ways.


In conclusion, a crucial document that specifies the specifications for a software system is the software requirement specification (SRS). It works as a roadmap for the software's development and a reference for both the development team and other parties involved. The functional and non-functional requirements of the software, including user needs, system interfaces, performance requirements, and any limitations or assumptions, should be precisely and concisely described in the SRS document. A strong SRS may significantly increase the likelihood that the project will succeed by ensuring that the software is created to satisfy the needs of the users and stakeholders.

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