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What are Various System Development Life Cycle (SDLC) Phases?

System Development Life Cycle or SDLC is a software development method or process. The System Development Life Cycle is used for developing complex systems.

Often complex projects are difficult to understand and composed of multiple components and subsystems. The software development process is organised into several logical steps to complete the project successfully.


There are diverse types of software development life cycle models defined, designed, and inculcated during software development processes. Each process model is unique in style and design; they are also in place to ensure the successful development of software. Among many, the following are the major and popular SDLC models being used in the industry:


Waterfall Model is a process for developing an entire system. It is an iterative process that involves breaking down the whole system into smaller tasks and designing the tasks so they can be completed in sequential order.

The waterfall model is the first of its kind. It is also known as the linear-sequential life cycle model. Its simplicity makes it one of the most used life cycle models. It is referred to as the linear-sequential life cycle model. It executes each phase of the programme line by line. The next phase in the development process can be executed only if the preceding one is successfully executed.

The strength of the waterfall model

The waterfall model’s simplicity is one of its main benefits. It is simple to comprehend and put into practice, making it the best option for small to medium-sized projects with clear needs. Additionally, it enables developers to identify problems early on and fix them before going on to the following phases.

The waterfall methodology also has the benefit of giving project stakeholders a crystal-clear road map. As a result, communication across teams within an organization is made easier because everyone is aware of what to anticipate at every level of growth.

The weakness of the waterfall model

There are also some weaknesses in the waterfall life cycle which are:

  1. There is a high amount of risk and uncertainty in using it
  2. The process within stages is difficult to measure and determine.
  3. It is not good enough for complex and object-oriented projects.


The Iterative Model is a well-known software development life cycle (SDLC) methodology that emphasises creating a functional prototype of the final product, testing it, and refining it in an iterative manner. It entails breaking down complex projects into smaller parts and developing them separately before integrating them into the final product. The model enables developers to identify errors early in the development process and make fast corrections, thereby decreasing the risk of project failure.

One of the major benefits of using an iterative model in SDLC is that it enables greater collaboration between developers and stakeholders throughout the project’s entire lifecycle. This continuous feedback loop ensures that the requirements of stakeholders are met and their concerns are addressed promptly. In addition, since each iteration builds upon the preceding iteration, there is a low risk of deviating from the requirements or design specifications.

The adaptability of an iterative model to changes in project scope or client requests during development is another advantage of employing this methodology.

Strength of iterative model

The iterative model is very efficient in:

  1. Producing results earlier and periodically
  2. Parallel development of plans
  3. Easy Testing and debugging during smaller iteration

Weaknesses of iterative model

  1. It requires highly skilled resources for risk analysis.
  2. It’s the phase processes; some system architecture issues may arise because all requirements are not gathered from the beginning of each phase execution.


Planning, Risk Analysis, Engineering, and Evaluation are the four phases of the Spiral Model. Throughout the software development life cycle (SDLC), these phases are executed continuously, with each iteration being referred to as a spiral. During the Planning phase, requirements are collected and analysed, and a plan for the remaining SDLC phases is developed. In the Risk Analysis phase, potential risks are identified and evaluated based on their likelihood of occurrence and impact on the success of the project.

Strength of the spiral model

  1. In the spiral model, changing requirements can be accommodated.
  2. Spiral allows for excessive use of prototypes.
  3. The spiral model help in a modular type of development, thereby helping in the successful management of risk.

Weakness of the spiral model

  1. The spiral model is very complex to manage
  2. The project end may not be known
  3. Spiral model processes are complex, and many intermediate stages are required for excessive documentation.


Has the name implies, V-model involves the execution of the phase process sequentially in a V-shape. V-model is an extension of the waterfall model and is based on an association testing phase for each corresponding development stage.

Strength of V-model

  1. The V – model is very easy to understand and apply and thereby easy to manage.
  2. It works effectively for smaller projects where project requirements are understood and unambiguous.
  3. It also involves a step-by-step execution of phases.

Weakness of V-model

  1. Like any other model, the v-model is also highly risky and very uncertain.
  2. Since it is simple and easy to use, it cannot be used for complex projects and object-oriented projects.
  3. Also, it is not suitable for projects where an element needs to be modified.


The agile software development method was developed as an alternative to the traditional approach. It is a method of software development that emphasises an iterative approach to designing and coding, with constant changes and adaptation. The SDLC agile model is based on a process that emphasises the importance of teamwork, collaboration, and communication to build a successful product.

The agile model is a software development and project management approach that emphasizes adaptive planning, continuous communication, and immediate feedback. The agile model is based on the principle that organizations should respond to change quickly and efficiently. This allows them to be more flexible and able to capitalize on opportunities as they arise.

In the traditional “waterfall” method, it is necessary to spend a long time planning and designing before coding begins. The waterfall method is followed by testing and verification, which can take as long as 18 months.

The agile approach was developed to make the entire process shorter, faster and more cost-effective. According to the agile model of SDLC, the whole process is broken down into small steps and should be finished in 3–8 months.

Strength of the Agile model

  1. The agile model is a very realistic approach to software development.
  2. It is suitable for both fixed and variable requirements.
  3. The agile model is straightforward to use and manage.
  4. It promotes teamwork and cross-training for developers.

Weaknesses of the Agile model

  1. The agile model is not suitable for complex development owing to its simplicity.
  2. Agile depends heavily on customer interaction, so the customer’s mistake can affect the effective working of the model.

Current Trends in the Life Cycle Modelling

Agile is the most popular and trending model being used in the industry. Agile introduces the concept of fast and reliable delivery to customers using a prototype approach. Agile is more popular in the industry today because of its many unique features, which allow customers to interact with the backbone of agile methodology and open communication with minimum documentation.

Agile methodology or system development life cycle models emphasizes rapid and flexible adaptation to change. It fosters collaboration among team members through short, frequent feedback cycles and allows for quick experimentation with new ideas. The goal is to deliver software products that are both reliable and on time.

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Raj Maurya

Raj Maurya is the founder of Digital Gyan. He is a technical content writer on Fiverr and freelancer.com. When not working, he plays Valorant.

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