What is the system development life cycle and why is it important?

The system development life cycle/systems development life cycle is an important process within the world of engineering and software development. Different sources provide a different idea of how many stages there are within SDLC and we will discuss that a little further down the line. However, the structure is what is both useful to know and efficient to use. This is got-to-know information for anyone in the field of development.

In this blog, we are going to give an overview of the model, how it works, and how it is implemented in software development specifically. In order to better understand how software development projects work and to give you something to take forward with you.

Let’s get started with a simple definition of the system development life cycle. 

What does SDLC mean? 

SDLC stands for the system development life cycle. It is a process used for systems engineering, information systems, and software development. There are variations of the model but the most widely accepted version contains either six or seven phases or stages. We will ascribe to the seven-stage model here, which is detailed as follows:

  • Stage 1: Planning
  • 2: Systems Analysis and Requirements
  • 3: Systems Design
  • 4: Development 
  • 5: Integration and Testing
  • 6: Implementation 
  • 7: Operations and Maintenance 

These stages, which we will discuss in more detail a little further down this blog, are the framework for completing any project of development or engineering. 

They encompass the entire process of development from start to finish, in a way that allows the best possible practice to ensue. In the world of software development, these stages allow an efficient, productive, and well-maintained project to be carried out and continued. 

The system development life cycle is, essentially, the guide to software development success.  

Different versions of the SDLC

As with software itself, there are different versions of the systems development life cycle. Three key options include: 

The Waterfall SDLC model

The Waterfall model is a classic and popular choice when it comes to the SDLC. It follows the basic premise of a physical waterfall, in that each stage is expected to naturally flow into the next, in a way that is continuous and in constant flux. However, you can’t typically go back and there must be forward movement throughout the waterfall. This applies perfectly to the sequenced flow of the SDLC in its steps. You will understand this more as you continue this blog and follow each step of the model for yourself.

The Agile model

The Agile way of working is common in the world of software and IT right now. It is a model that puts the customer and their needs first, focusing primarily on user experience. This means that in each stage of an Agile SDLC model, user feedback and experience are critical to each decision made. Agile models tend to release their software quickly and make frequent updates and upgrades to these systems. All of these upgrades will focus on feedback received from users, thus allowing their experience to take priority.

The Iterative development model 

Thirdly, the Iterative development model is one in which the development and implementation of software come quickly. This model is often used subject to demand when there is something needed promptly by a large user base. Similarly to an AGILE approach, these deployments are intended to be upgraded and improved upon as time goes on. Rather than allowing lots of time in the earlier steps of the model, we see more time spent in the final few.

This process will become more clear as we talk you through each individual step of the system development life cycle. 

With that in mind, let’s take a look at each of the stages in more detail individually. Each one is as important as the next and the entire model can’t function successfully without each stage being carefully implemented. Therefore, it is pretty important not to leave anyone behind. 

Stage 1: Planning 

The planning stage of the systems development life cycle is also commonly known as the feasibility stage. This is the starting point of all future work and it is hugely important that it is engaged with thoroughly in order to smooth out any future creases in your project. 

When it comes to software development, this stage will focus on aspects such as:

  • How long a project will take
  • What budget exists
  • What features, functions and capabilities are needed
  • If replacing an existing system, what needs replaced/fixed/optimised
  • Calculating any costs involved, including team pay, material costs, and other
  • Feedback from investors/clients

The planning stage is vital to the entire project. It is at this stage that many developers will plan project sprints and relay this information back to clients and/or other members of their team. If this isn’t calculated well, it can hold the project back in a variety of ways. Complete and correct planning could, as such, be something that takes up a decent chunk of time in the development process. 

Stage 2: Systems analysis and requirements

The second part of the systems development process will be system analysis and requirements. At this stage of the software development life cycle, we are moving into the finer details of the project and its spec. 

This stage, as the name suggests, is all about requirement and need. Here, we are thinking about what the project needs, what the software needs, what the client needs, and what we need. We are anticipating every possible need that could arise in one singular project. 

Once such requirements on each level have been established, it is possible to move on to structuring how those needs will be met through your specific software. If the software you are creating doesn’t serve certain purposes and needs, then it is a real stab in the dark. 

Appropriately moving through the system analysis and requirements stage of the life cycle helps to keep the project productive and efficient. It helps guide the actions of future steps and helps to keep the proposed system solution-orientated.

Stage 3: Systems design

Moving on to stage 3, we have the systems design phase of the project life cycle. This is where the new system or software is designed and definitively laid out prior to any coding beginning. Sometimes pseudocode is developed here alongside prototyping. This allows the earliest “soft” version of the software to be developed before anything too concrete comes into play and it becomes harder to change. 

During this development phase, the necessary specifications for the software will be drawn up and agreed upon. This is the final planning stage before we move into the tangible development stages. 

Last chance to make sure everything is in order and ready to go before the coding begins.

Stage 4: Development 

By stage 4, we have reached the step in the development cycle where the “real work” can begin. This development phase marks the beginning of coding and laying down the work to build the new software. 

The software development methodologies will draw on what has been identified in all of the earlier stages. Planning, system analysis and systems designs will all provide the backbone for the software that is developed here. The design of the last stage will be particularly important and will be used to inform all coding decisions going forward. 

As with all stages in the system development life cycle, project management will be an important aspect of the development stage. This is the point in the life cycle in which everything and everyone needs to pull together to work towards one specific goal. The development teams involved will need to be on the same page in order to stay solution-focused, and, indeed, focused on the same solution and outcomes for the project. 

Stage 5: Integration and testing

In our journey through the systems development life cycle (SDLC), the next phase involves systems integration and testing. Of course, it is not enough to simply build software and roll it out to clients or on a live system. The software we now have from stage 4 needs to be tested for bugs, loss of quality, and failure to meet any specified requirements. 

The software testing phase of the life cycle is key. The finished product needs to meet all of the goals and specifications outlined in the earlier steps. Without doing so, it may be a finished piece of work but it won’t be the piece of work we were aiming for, and this achieves very little. For good quality, professional, advanced software, testing is essential to best practice. 

In this stage, QA teams (quality assurance) will work with software integration and testing to make sure everything is in order. This may include a couple of rounds of back and forth while things are fixed and brought into line. Such is the normal process of a system development life cycle. 

Once everything has passed, we can move on to our next stage in the development process.

Stage 6: Implementation

The implementation stage of the software development life cycle is also commonly known as the deployment stage. This is the point at which our new system can be phased in to replace an existing system or launched as entirely new hardware or a new software system. 

Although this might seem like one of the simpler stages in the system development life cycle, it can, in reality, be one of the more complex. 

In the implementation phase, there will always be teething issues. Especially so if you upgrade a system or server that already exists. At this development stage, we might experience more bugs and feedback than we did at the testing stage. 

Integrating upgrades and launching new software systems will take some time, patience, budget, and maybe even a dip or two into earlier stages. However, it is a critical stage of the development cycle and no success can be made without it. It is simply one of those times where you need to cross your fingers and hope that the hard work you put into the earlier stages will see you through.

Stage 7: Operations and maintenance 

At the seventh and final stage of our life cycle, we have operations and maintenance. This is where our software is live and out in the wild but remains under review and maintenance as it continues this new life. 

Again, we might see bugs at any point in a software’s life. To maintain the best possible experience for your users and/or clients, appropriate support and maintenance will be important. 

At this stage, we may also see the release of updated versions of the software. Improving and adapting as time goes on and feedback rolls in is critical for the best possible service. 

This development cycle stage is not short-lived, it is a long-term phase that will continue as long as your team is committed to the software it has launched. So as the life cycle completes with this step, it also continues with this step for a while to come. 

To wrap up…


All in all, the system development life cycle is a critical part of software development. It is integral to the work that is done and how it is framed by teams across the world. Using the cycle allows for successful and predictable results in each and every piece of software you develop and launch. 


There are different ways in which you may use the model, as we have seen earlier in this blog. But, however you do use it, it is a systematic approach that breeds efficient, streamlined and successful work. 


If you need digital transformation in your life, talk to us at 6B digital. We have a wealth of practical experience in helping organisations in a range of sectors replace outdated processes and systems and transition to a better way of working – and we could do the same for your business.


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