Software Development Life Cycle: Definition & Phases

October 24, 2023

SDLC software development life cycle is important for software development companies. It helps to avoid chaos in the work to handle product development tasks in a structured way, following a well-defined plan that will ultimately lead to a successful result.

Next, we'll take a closer look at what SDLC is, what stages are included in the software development life cycle, and look at the Four-ages case.

What is the software development life cycle?

Software development life cycle is generally the process of planning, developing, and maintaining software (for PCs, mobile phones, and so on).

Following the SDLC methodology makes optimizing the final result and achieving all the goals planned at the initial stage possible, e.g., making a product within the budget, in accordance with the client's expectations, qualitatively, strictly within the deadlines, bringing profit to the client's business in the long term.

This so-called plan is referenced by developers, project managers, and other stakeholders working on the projects, and it ensures unity of action throughout the software development process - ensuring quality, reducing hiccups, and streamlining the transition from concept to ready-to-use software.

Software development cycle: why is it crucial?

  • Thanks to the software development cycle, the team working on product development understands clearly what is required of them and the goal for the final software outcome.
  • Also, the development of the SDLC cycle allows early identification of risks.
  • One of the main advantages of the SDLC cycle is that it gives a step-by-step realization of the solution, e.g., prototyping or writing functional specifications.

What are the phases of SDLC?

  • Ideas generation
  • Planning
  • Visualization of the future product
  • Active coding/development
  • Testing
  • Deployment
  • Maintenance & operations

More about each system development life cycle stages read below.

SDLC cycle: preliminary planning & determining the project scope

This is the most essential of the software development life cycle phases because if you do not start the working mechanism correctly, it will go wrong and not give the desirable results.

After the client and the vendor have given the start of the project, the vendor's project manager appoints a project team. Together with the customer, they define the scope of the project by gathering and analyzing requirements.

At this stage, it is important to develop business goals, requirements, and specifications and consider all possible risks. It is essential to discuss what will be needed to achieve the goals. Think through all the details to get the result, namely the end product for the customer, through the same analysis, planning, design, development, testing, and launch.

SDLC cycle: analyzing the requirements & completing the plan

Team members who might be involved in this phase: Product Owner, Project Manager, Business Analyst, CTO.

After discussing the ideas with the client, we have a clear vision of the desired product and the team's expected outcome. The next step is to consolidate this into a structured plan.

  • Analyze all the requirements, research, and planning based on the fact that the end product should meet your expectations, especially (first and foremost) the customers' expectations.
  • At this stage, we need to not only refine the project plan but also develop a work breakdown structure and formulate a design plan.
  • The team should determine the price and the resources to be spent and how much of them will be needed to solve all the tasks. It is also critical to calculate the risks and develop a sub-plan to minimize them.

To summarize this phase of the SDLC cycle: The team needs to develop a plan for all participants (developers, designers, testers, etc.), determine the feasibility of the project, and how they can successfully finish it with minimal risks and costs.

Then, all parties review the plan and provide feedback and suggestions. Having such a plan is important to gather more input from everyone into the same document. A failure at this step will result in high costs or, possibly, even a project collapse.

SDLC system development life cycle: System Design & UX mockup creation

Team members who might be involved in this phase: System Architect, UX/UI Designer.

The project specifications from the previous step are transformed into a design plan (Design Specification). This is the stage of creating Unified Modelling Language (UML) diagrams (UML) and mockups. Essentially, this is also a planning and task structuring phase.

Numerous tools for developing diagrams & mockups, such as Adobe XD, Figma, InVision, and, simplify the process of creating a visual representation of the work from idea to completion. This visualization will help better understand and manage the development process, ensuring it is organized and consistent.

Software development process steps: example of mockup (what the product should look like & sequence of execution)


It's essential here to break down the work stages into a diagram of the software development life cycle.

The SDLC cycle diagram example (steps of software development & execution order)

Source: Virtasant

Each of these steps is represented as a separate block, from which arrows will emanate, indicating the direction from one phase to another based on the sequence of execution. This can be represented in the form of a cycle, a linear sequence, or another form depending on the SDLC model chosen (we will tell you a bit about software life cycle models below).

Note. The SDLC diagram assists all project participants in grasping the overall picture, understanding the project's current state, and planning the next steps.

Lifecycle of software development: bringing the design to realization

Team members potentially involved in this phase include the front-end and back-end developers.

And now, we have come to the central and one of the most time-consuming stages of software development - coding. This is where the process begins, where each developer adheres to the created plan/specifications.

At this stage, clear coding style guidelines and best practices are vital to maintain order throughout the project. Establishing rules for variable naming and directory structuring ensures organized and consistent code, making it more understandable and testable.

To ensure the effectiveness of the development process, task management systems like JIRA, Redmine, or Basecamp are used.

Developers clearly understand what needs to be done, while managers can monitor the progress.

Software development life cycle process: analyzing the bugs & defects of various types

Team members who may be behind this phase: Developers, QA Engineers, Product Owners.

The SDLC software development life cycle methodology helps to avoid costly mistakes, namely resource and, at the same time, reputational losses.

The testing phase significantly contributes to it. The more testing - the fewer corrections will be required in the future, the less precious time and money will be spent, and the reputation of the company will be better.

In this phase of the SDLC cycle, the Quality Assurance (QA) engineers meticulously test the software to ensure its quality and functionality align with the expected outcomes. They use a variety of testing methodologies, such as:

  • Functional Testing: To ensure the software's functions operate per the requirements.
  • Integration Testing: Ensuring that different software components work seamlessly when integrated.
  • Regression Testing: Verifying that new changes haven't adversely affected the existing functionalities.
  • Performance Testing: Checking the system's responsiveness and stability under different conditions.
  • Usability Testing: Evaluating the software's user-friendliness and overall user experience.
  • Security Testing: Probing the system for potential vulnerabilities and weaknesses.

As these tests are carried out, any discrepancies, bugs, or issues are reported back to the development team. The developers then prioritize and fix these bugs, ensuring the software is free of critical and significant defects. The QA and development teams often implement tools like JIRA, Bugzilla, or Trello for effective bug tracking and collaboration.

Continuous communication between the QA and development teams is vital to ensure all identified issues are addressed promptly during this phase of the SDLC cycle. Once the QA team is satisfied with the software's stability and performance and all the critical problems have been resolved, the software can move into the Deployment phase.

SDLC software development life cycle: launching the product

Team members who may be behind this phase: Product Owner, Project Manager, DevOps.

Now comes the SDLC software development life cycle stage – deploying the product, handing it over to the customer, and launching it to users. Some companies' services may include marketing the new product (helping the customer's target audience know that the software has been released), e.g., launching on platforms such as Product Hunt.

At this stage, in order to launch the developed product to end users, it is usually deployed to a server. It might or might not use Kubernetes. If you created a mobile app, you must upload it to the app store.

Many software development outsourcing companies prefer a phased deployment approach. It involves releasing the product in beta mode, allowing users to test its features thoroughly. Feedback gathered during this phase is invaluable, helping refine it to suit the target audience better.

After that, you can already release the final paid version of the software and get more positive results regarding registrations and sales.

Product life cycle software development: maintenance & operations

Team members who may be behind this phase: Users, Testers, Support managers.

This stage of the software development life cycle consists of support and operation, meaning that you need to check the documentation and the effectiveness of the work done.

The project team takes care of the developed product even after its release, improving it at the customer's request and constantly fixing functionality problems.

This stage might not be present in some SDLC methodologies if the agreement specifies that the project concludes upon product deployment. This typically happens when production has been finalized and approved by the client, and you have handed over your work.

Sometimes, it's pre-agreed that the product won't be left unsupported. Instead, one or more developers will be assigned for ongoing support, with separate compensation for this service.

Software life cycle models: what are the basic models?

  • Waterfall
  • Agile
  • Iterative
  • V-shaped
  • Big Bang
  • Spiral

Now let's take a closer look at each model in the chart.

Your Table
SDLC Model Unique Aspects of the Software Life Cycle Models
Waterfall One of the most popular software life cycle models based on a sequential development process. It means that each phase starts only after the previous one is completed.
Agile Iterative approach that emphasizes flexibility, collaboration, and customer feedback. It involves breaking projects into small, manageable pieces called 'sprints' or 'iterations', typically lasting 2-4 weeks, with regular reviews and adjustments as the project progresses.
Iterative Software development process based on well-defined baseline requirements. This SDLC model is built on rapid, small cycles. First, a very simple product version is made, then gradually improved.
V-shaped A model with simultaneous development and testing at each stage to ensure quality.
Big Bang Bing Bang is one of the riskiest software life cycle models. Development without precise planning, where details are figured out as you go along.
Spiral A combination of an iterative model and a V-shaped with a focus on risk analysis and management.

Read more about each point in the article Software life cycle models.

SDLC methodology: A Simple Case Study

A company in California, known for sharing APIs (these are like building blocks for software), wanted to create a big hub for distributing these APIs. They teamed up with Four Ages Software to make this idea come to life, and the journey lasted three years.

They started with a small team, but as the work grew, so did the team. They had a flexible plan (SDLC methodology/Agile), which allowed them

  • tackling different tasks step by step, like creating a user-friendly interface,
  • setting up payment systems,
  • and ensuring that the software could handle a lot of use without crashing.

To keep everything on track, they used a method called Scrum. It helped them break down big tasks into smaller, manageable chunks and kept everyone in the loop about what needed to be done next.

Tools like Jira and Slack helped them track progress and communicate efficiently.

One impressive feat was building a system that could handle up to 10 million requests per second, showing that with good planning and a step-by-step approach, you can build powerful and reliable software.

They also made sure to test the software thoroughly to catch any issues and put in measures to keep the data secure.

This story shows how having a good Software development life cycle plan and a flexible approach can help turn a complex idea into a successful software project, step by step.

Find out this case and others here.

SDLC methodology: a brief summary of the main points

Software development life cycle is, in general, the process of planning, developing, and maintaining software (for PCs, mobile phones, and so on).

SDLC is essential for software development companies because it helps avoid chaos in handling product development tasks in an organized way, following a well-defined plan that will ultimately lead to a successful result.

Main software development life cycle steps: Ideas generation, Planning, Visualization of the future works, Active coding/development, Testing, Deployment, and Maintenance & operations.