Software Development Life Cycle (SDLC), its Phases and Popular Models

Software Development Life Cycle (SDLC), Its Phases And Popular Models

This article explains what is Software Development Life Cycle (SDLC), how it works, its phases & the most popular SDLC models with the pros & cons of each.

The Software Development Life Cycle has become a crucial part of the Information Technology industry today. SDLC has undergone many changes and is evolving through the ages of big data, cloud delivery, AI/ML automation. Still, it serves as a critical framework for understanding the distribution of software products.

The Software Development Life Cycle is commonly defined as “A process that produces software through several keep stages, to implement quality and efficiency.”

SDLC defines the complete cycle of development of software, that is, all the tasks involved in planning, creating, testing, and developing the software.

In this blog, we are going to get a broad view of different phases of SDLC, the benefits of SDLC, and its models.

What is the Software Development Life Cycle?

The Software Development Life Cycle is a process that produces software with the highest quality and lowest cost in the shortest time possible. It provides a well-structured flow of phases that helps a company to quickly build high-quality software that is well – tested and ready for production use. The SDLC involves six phases, namely:

  1. Requirement analysis
  2. Defining requirement
  3. Designing
  4. Building development
  5. Testing and
  6. Deployment

Why is SDLC relevant?

SDLC is essential nowadays, and it believed that using the exact life cycle model, the development of software would be systematic and disciplined. SDLC helps to develop a clear understanding between the representatives of a different team of developers while developing the software. This understanding is vital to avoid any kind of chaos and project failure, which may lead to a significant loss of time and resources.

How SDLC works?

SDLC works by lowering the cost of software development while the quality of the software is improved, and the production time is reduced. The two divergent demands are achieved by following a plan where typical pitfalls of software development projects are removed. This plan is started by evaluating the existing systems for deficiencies and, at the same time interacting with customers asking for their needs. This is followed by defining the requirements needed for the new system. The software is done created by the company to the stages of analyzing, planning, designing, developing, testing, and deploying.

In SDLC, a strong focus is given on the testing phase. Many companies generally spend few efforts on testing, while a sharper focus on testing can save them from a lot of river, time, and money. The company and its steam should be smart and must follow the right types of tests.

Software Development Life Cycle Phases
Dzonatas / CC BY-SA

Phases of Software Development

Requirement analysis

In the first step, the analysis of problems or defects of pre-existing software is analyzed. To develop new software, communication with users and customers is required, where they are used for their requirements and desires. This communication is done by a senior member of the organization. He should be experienced enough to understand what the customer wants. At the same time, he needs to decide how to execute it properly. The senior member should also be able to determine if the demand is practical or not and identify the risks, failure, and limitations associated with the development of that particular project.

For example, if a school or college wants the software to keep account of each student and their performance in academics and co-curricular activities, they might contact a software developing company and tell them about their requirements.

Defining the requirement

The second step includes officially documenting all the requirements made by the customer in the form of software requirement specification, SRS, and get it approved by the customer. It is done to verify whether the team is clear of what exactly the customer wants and to avoid any kind of legal issues in the future. At the same time, the required labor, investment, resources, and time is calculated in this step.

Designing the software

In this step, sum-product architectures are shortlisted. The pros and cons and limitations of these architectures are listed in design document specification, DDS, and then the best architecture is selected.

Building/developing the software

This is where the actual development of software is done. The most critical step in software development is generating the code of the software with the help of a compiler interpreter and debugger. It is also imperative to select the best-suited programming language according to your project.

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Testing is the subset of all the phases in SDLC. Everything you have designed so far needs to be tested. In this space, potential errors are identified, then detected, followed by reporting them, and finally tracking the location of these errors and fixing them. This step is followed by a retest to see how the performance of the software has enhanced. This testing needs to be done until the time when the software meets all the quality standards written in the SRS.


After everything is finalized, the software is finally released in the market. But, there is still a lot of things to do. When the software is published in the market, feedback from customers is taken. Some feedback can be positive, and some can be negative. Taking the view of the negative responses, the software needs to be upgraded and, if required, re-released. Hence, this stage, also known as maintenance is crucial.

Benefits of software development

If SDLC is correctly followed, it allows the highest level of management control and documentation. The developers are well aware of what they are supposed to build and why. It reduces the scope of friction among all the parties and their representatives. So the resources are very judiciously used.

Interaction with customers and stakeholders, in the first phase of system development and life cycle also helps the company understand the requirements very well. No communication with customers and stakeholders can result in an understanding of the system requirements and the outset, which may also lead to a fall in market demands and relevance of the software.

If a company does not use system development and life cycle phases, they may lack a proper procedure on how to build software. So it may result in the execution of the wrong step at the wrong time.

In the second phase of SDLC, which involves making a legal document, also called software requirement specification, SRS, any scope of fraud from the side of the client or the company is minimized to a terrific extent.

SDLC is perfect for estimating the total cost of the project too. Calculating the total cost of the project can minimize any scope of mischievous activity by the workers or contractors, and it increases the efficiency of the developing team.

Software Development Life Cycle Models

A software life cycle model is a representation of SDLC. Among all the models, the primary phases and activities remain the same.

Software Development Patterns Or Models
BeaoOld waterfall: Paul Smith / Public domain

Waterfall Model

The waterfall model, also known as the linear sequential model, is the first model that is used in SDLC.

In this model, the outcome of a particular phase is the input for the succeeding stage. The development of the next step starts when the previous period is complete.

Waterfall Model
Peter Kemp / Paul Smith / CC BY

Advantages of the Waterfall Model:

  • The waterfall model is simple and can be easily understood. Here, the one in which all the phases are done step by step.
  • This model leads to no complexity.
  • And this model makes the project easily manageable.

Disadvantages of Waterfall model:

  • The model is time-consuming & cannot be used in small projects.
  • If a project has uncertain requirements, the waterfall model cannot be used.

V-Shaped Model

V-Model is the short form of the Verification and Validation Model. In this model, Verification (development) and Validation (testing) go simultaneously. The V model and the waterfall models are very similar. As compared to the Waterfall model, the test, planning, and testing commence is done at an early stage in V-Model.

V Shaped Model
Leon Osborne, Jeffrey Brummond, Robert Hart, Mohsen (Moe) Zarean Ph.D., P.E, Steven Conger ; Redrawn by User:Slashme. / Public domain

Advantages of V – Model:

  • It is simple and easy to understand the model.
  • V –The model is suitable for smaller projects where the requirement is defined.
  • It is systematic and disciplined and hence, results in a high-quality product.

Disadvantages of V-Model:

  • A V-shaped model is not advisable to apply during ongoing projects.
  • Requirement change at an early stage might be expensive.

Prototype Model

In this model, the prototype is developed before the actual software.

Software prototypes are built before the actual software to get valuable feedback from the customer. Customer feedback and the requirement is used to modify the prototype and is again presented to the customer for evaluation. This cycle continues until the customer is satisfied with the software.

Advantages of Prototype Model:

  • Since the defects are found much earlier, this model reduces the cost and time of development.
  • Any missing feature or functionality or a change in requirement can be identified and worked upon in the evaluation phase itself.
  • The involvement of a customer from the initial stage minimizes any scope of confusion.

Disadvantages of Prototype Model:

  • Since the customer is involved in each phase, there is a danger of increasing the complexity of the project and sometimes maybe even time-consuming. Moreover, not all consumers are experts in software, so involving a layman is not always a good idea.

Spiral Model

The Spiral Model consists of iterative and prototype approach. Its phases are followed in the iterations.

Spiral Model has four phases:

  • Planning
  • Risk Analysis
  • Engineering
  • Evaluation
Spiral Model
Connyderivative work: Spiral_model_(Boehm,_1988).png: Marctroyderivative work: Conan / Public domain

Advantages of Spiral Model:

  • An extensive risk analysis is done.
  • in the next iteration, Any required enhancement or change in the functionality can be done

Disadvantages of Spiral Model:

  • It’s not advisable to use the spiral model for small or medium projects. This model is best suited for large projects only.
  • The project can be very costly if the number of iterations is more.

Agile Model.

The Agile System Development Life Cycle model divides the product into different cycles, which results in delivering the desired working product quickly. The products are released regularly, and feedbacks are collected from the users. Based on the feedback, corrections are made.

Agile Software Development
Abrahamsson, P., Salo, O., Ronkainen, J., & Warsta, J. / CC BY-SA

Advantages of Agile Model:

  • It gives more flexibility to developers.
  • Any new feature can be added without much technical hindrance.
  • The customer is satisfied as the feedback and suggestions are taken at every stage.

Disadvantages of Agile Model:

  • Documentation is not available.
  • Applying this model requires highly skilled developers.
  • The project can fail if a customer is unable to explain what he exactly wants.


To make a software development project successful, sticking to a suitable life cycle is very important. This also makes management of the project more manageable.

Choosing a Software Development Life Cycle model is very important. Every Software Development Life Cycle model has its own advantages and disadvantages. Hence, the best model for any project can be determined by considering factors like a requirement, system complexity, size of the project, budget, and skill limitation.

The information mentioned above helps to show why the Software Development Life Cycle is significant and how the cycle has evolved.

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