SDLC vs STLC: What’s the Difference 2024

    Software drives everything from coffee makers to satellites today, so understanding the process of its creation is more vital than ever. Enter the world of SDLC vs STLC. While these acronyms might sound like tech jargon, they’re fundamental in understanding how software comes to life and how it’s perfected. 

    SDLC, or Software Development Life Cycle, sketches the grand journey of software from an idea to a usable product. On the other hand, STLC, the Software Testing Life Cycle, ensures this software is polished, flawless, and ready for prime time. 

    Together, these processes make certain that the apps you love, the websites you browse, and the systems you rely on, are at their best. So, buckle up! We’re about to unravel the intricate dance between SDLC and STLC, shedding light on each step of their harmonious ballet.

    What is SDLC

    What is SDLC?

    Alright, picture this: you’re building a house. You wouldn’t just start slapping bricks together, right? You’d start with a plan, lay a foundation, build walls, and then add the roof. The Software Development Life Cycle (SDLC) is kinda like that, but for software projects. 

    It’s a step-by-step process to take an idea for a software project from its inception all the way to its completion. It ensures that we’re not just throwing code around, but creating quality software efficiently.

    What are the Different Phases of SDLC?

    SDLC in software testing consists of multiple phases which are crucial to understand. So, let’s get started —


    This is where all great software projects start. Think of it as sketching out your dream home. What features do you want? What’s the purpose? Budget and timelines are set here.


    Once we know what we want, it’s time to dive deeper. This phase is about understanding the nitty-gritty of the requirements. Like, figuring out the best materials for your house.


    Now, we start visualizing the final product. This is where developers decide on the architecture and design elements, similar to drafting a blueprint for a house.

    Implementation (or Coding)

    Time to get our hands dirty! This is where developers start writing the actual code. It’s like laying down bricks and putting up walls.


    No one likes a leaky roof! Before we declare our software ready, it undergoes rigorous testing to catch any glitches or errors.


    Hooray! The software is ready. Just like unveiling your new home, this phase is about launching the software for users.


    Just like a home, software needs regular upkeep. We fix any unexpected bugs and make updates as needed.

    Key Feature of SDLC

    When diving into the realm of software development lifecycle, there’s a lot to unpack. Have you ever stumbled upon the terms SDLC and STLC and scratched your head? Well, let’s unravel that mystery a bit.

    Imagine SDLC as the master plan behind creating a software masterpiece. But what truly makes it stand out?

    All-Encompassing Vision

    SDLC is not just about coding or testing. It’s a holistic approach, guiding a project from a mere idea to its final launch. While there’s often discussion about the difference between SDLC and STLC, think of SDLC as the full journey. It encompasses the entirety of software creation, while STLC focuses mainly on the testing phase.


    One of SDLC’s shining features is its versatility. Depending on a project’s needs, it can be tailored. Whether you’re leaning towards the Waterfall model or an Agile approach, SDLC flexes its muscles to fit the bill. 

    It’s not just a fixed roadmap but a dynamic guide adapting to the terrain.

    Feedback Emphasis

    Building software isn’t a one-shot deal. It’s an iterative process, and SDLC recognizes that. Throughout its stages, there’s a constant loop of feedback and refinement, ensuring the end product isn’t just functional, but exceptional.

    Risk Management

    SDLC isn’t just about building software; it’s also about foreseeing potential pitfalls. By identifying risks early, teams can devise strategies to mitigate them, ensuring a smoother development journey.

    Stakeholder Involvement

    From the get-go, all stakeholders – be it developers, testers, project managers, or clients – are involved in the SDLC process. This collaborative approach ensures everyone’s on the same page, and feedback from all corners is considered, leading to a more rounded product.

    Predictable Outcomes

    With a structured approach, SDLC offers more predictable timelines and outcomes. When everyone follows the set stages, it reduces the chances of unexpected delays or results. It’s like having a reliable recipe for software success.

    Continuous Improvement

    Post-launch, SDLC doesn’t just wash its hands off the project. Continuous monitoring and updates are part of the process, ensuring the software stays relevant and efficient as technology and user needs evolve.

    Why SDLC?

    You know, in the software world, it’s easy to get caught up in the technicalities and forget the bigger picture. And this is where the ever-reliable SDLC comes into play. 

    But why choose SDLC amidst all the buzz about SDLC vs STLC and the myriad of other software methodologies out there?

    Comprehensive View

    SDLC isn’t just a list of tasks to tick off. It’s about seeing the whole picture, the entire journey of a software project from inception to retirement. It’s not just about how the software is built, but why it’s built that way, for whom, and how it will evolve over time. 

    This holistic view ensures that projects align with business objectives and user needs.

    Proactive Problem Solving

    With SDLC, we’re not just waiting around for issues to crop up. By its very design, it anticipates challenges and equips teams to handle them head-on. It’s the ounce of prevention that often saves a pound of cure down the road.

    Consistent Quality

    While debates around SDLC vs STLC emphasize the distinctions, it’s essential to note that SDLC provides a framework ensuring consistent quality throughout the software’s life. 

    From its initial design to eventual updates, the emphasis is on creating a product that stands the test of time.

    What is STLC

    What is STLC?

    If SDLC is the broad roadmap of creating software, STLC, or Software Testing Life Cycle, is the magnifying glass that zooms in on one crucial aspect: testing. Think of STLC as that meticulous friend who checks every detail before making a decision. It ensures that the software not only works but works flawlessly.

    What are the Different Phases of STLC?

    Below are the phases of STLC that you must know about —

    Requirement Analysis

    Before we dive into testing, we need to know what we’re testing for. This phase is about understanding the software’s requirements, figuring out what the client wants, and what the end-users need. It sets the stage for everything that follows.

    Test Planning

    Here’s where the real groundwork starts. Testers draft test specifications, determining the scope of testing, the tools they’ll use, and the timelines. It’s like prepping your toolkit before fixing a gadget.

    Test Design

    With a plan in hand, testers now design the actual test cases, procedures, and criteria. They decide what scenarios they’ll simulate to check the software’s mettle.

    Test Environment Setup

    No, it’s not setting up desks and chairs. It’s about configuring the software and hardware environment to simulate real-world conditions for testing. It ensures that tests are as close to real user scenarios as possible.

    Test Execution

    The action-packed phase! Testers run the designed tests on the software, looking for bugs, glitches, or any other issues.

    Key Feature of STLC

    So, what makes the Software Testing Life Cycle (STLC) so unique and indispensable?

    Precision Focus

    Unlike broader methodologies that look at the entire software creation process, STLC hones in specifically on testing. Every phase, every step is meticulously crafted to ensure the software performs impeccably under all scenarios. 

    It’s all about the details, ensuring nothing slips through the cracks.

    Bug Tracking

    One of the hallmarks of STLC is its structured approach to identifying, documenting, and tracking bugs. When an issue arises, it’s not just about fixing it, but understanding its root cause to ensure it doesn’t recur. 

    It’s like detective work, but for software!

    Real-world Simulation

    STLC isn’t about testing software in a vacuum. It’s about setting up real-life environments and scenarios, mimicking how end-users will interact with the software. 

    By doing this, STLC ensures that when the software finally reaches its audience, it’s ready for anything the real world throws its way.

    Consistent Feedback

    STLC isn’t a one-and-done deal. It thrives on feedback. After each test, results are analyzed, shared, and used to refine the software further. It’s a loop of continuous improvement, making sure the software gets better and more robust with each cycle.


    Testing isn’t a solitary task in STLC. It fosters collaboration between developers, testers, and stakeholders, ensuring everyone’s insights and expertise contribute to a well-rounded product.

    Why STLC?

    With all the talk about software creation, from brainstorming ideas to finally launching it, why do we even need STLC? 

    Let’s dive into why this unsung hero of the software world deserves its own standing ovation.

    Beyond Just Functionality

    Sure, a software might work, but does it really work? STLC isn’t just about ensuring software functions, but that it functions optimally in every scenario. It’s about delivering a seamless experience, not just an operational one.

    Confidence in Deployment

    Imagine rolling out software, fingers crossed, hoping users won’t run into issues. Sounds nerve-wracking, right? With STLC, there’s a confidence that comes from rigorous testing. 

    It’s like rehearsing thoroughly before the big show, ensuring every move is pitch-perfect.

    Economical in the Long Run

    Catching issues early with STLC can save heaps in the long run. Addressing a bug during development is often simpler and less costly than after deployment when users are already affected. 

    Think of STLC as the safety net catching issues before they escalate into costly catastrophes.

    User Satisfaction

    At the end of the day, it’s all about the users. STLC ensures that when users interact with the software, they’re met with a smooth, bug-free experience. Happy users mean better reviews, more referrals, and overall success. 

    STLC is like that secret recipe ensuring your dish isn’t just palatable but utterly delightful.

    How does SDLC fit with STLC?

    In the bustling universe of software development, you’ve likely heard the terms SDLC and STLC being tossed around. Some might see them as two separate galaxies, while in reality, they’re more like interconnected constellations. 

    Let’s dive into the harmonious dance between them and unravel the ever-evolving debate of SDLC vs STLC.

    The Creation and the Critique

    Imagine painting a masterpiece. SDLC is the artist, sketching, and painting the canvas, while STLC is the keen-eyed critic, analyzing every brushstroke for perfection. They’re two parts of a single journey: creation and validation. 

    The essential difference between SDLC and STLC is the focus; while SDLC looks at the software’s entire lifecycle, STLC narrows down to its testing aspect.

    Building Blocks and Quality Checks

    As different software components come to life during the SDLC, STLC steps in, ensuring each block not only fits but fits perfectly. It’s a tandem process. As SDLC crafts, STLC polishes.

    Two Sides of the Same Coin

    Though there’s a clear stlc and sdlc difference, they’re intrinsically tied together. One is incomplete without the other. SDLC provides the framework, the blueprint. 

    In contrast, STLC ensures that this blueprint, when brought to life, stands robust against real-world scenarios.

    Difference between SDLC and STLC

    Difference between SDLC and STLC

    A few days back, I was conducting some interviews. I was surprised to see some candidates were not able to explain simple concepts like SDLC & STLC. Everybody was giving me very standard answers. SDLC – a systematic approach to developing a software and STLC – testing process of a software in a systematic and planned way. No one explains me logical Differences & Similarities between these two.

    My question is very simple – How you can relate six phases Requirement, Design, Development, Testing, Deployment & Maintenance to Software Testing Life Cycle?
    Let’s see how I related these six phases with STLC —

    S. No.PhaseSDLC – Software Development Life cycleSTLC – Software Test Life Cycle
    1Requirements GatheringRequirements gathering is done by business analyst. Development team analyze the requirements from the design, architecture & coding perspective.Testing team also review & analyze the requirements. Testing team identifies the testing requirements like what types of testing will be required and review the requirements for logical functional relationship between various features / modules, so that any gaps can be caught at an early stage.
    2DesignTechnical architect works for the high level & low design of the software. Business analyst works for the UI design of the applicationHere, test architect generally the test lead/manager, does the test planning, identify high level testing points. Basically, requirement detailing is done in this phase.
    3Coding or developmentDevelopment team does the actual coding based on the designed architecture.Testing team write the detailed test cases.
    4TestingIn SDLC, actual testing is carried out in this phase. It includes unit testing, integration testing & system testing etc..Test Execution and bug reporting, manual testing, and test automation are done, defects found are reported. Re-testing and regression testing is also done in this phase. But, I don’t agree with this statement. So, if I want to relate the testing phase with STLC, I would say it it is testing of test cases & test plans i.e. is basically review of test cases, test scenarios etc..
    5DeploymentApplication is deployed on production environment for real end users.Final testing and implementation is done is this phase and final test report is prepared. For this statement as well, I don’t agree. For software / application deployment is basically, when it is installed for real use. So, this way, STLC, deployment would be when test when test cases getting used i.e. execution of test cases.
    6MaintenanceBasically, it includes, post production / deployment support & enhancements.Most of people say – Maintenance testing is carried out in this phase. My definition for this is – updation & maintenance of test plans, test case required for the testing of support requests & enhancements as a part of maintenance.

    There are two sides of this coin —

    • Testing within the software development (Here, the old definition of STLC may be applicable)
    • Consider testing as an independent sub-project of a software development project (Here, I believe, old definition no longer sustains)

    Wrapping up

    When it comes to software development and testing, the dynamic duo of SDLC vs STLC emerges as the backbone of creating robust, user-friendly digital solutions. SDLC creates software’s form and functionality, but STLC makes sure it stands up to every challenge, ironing out potential wrinkles before they become visible.

    The marriage of these processes ensures that what reaches the end-user isn’t just functional, but exemplary. In summary, if SDLC is the heart pumping life into software, STLC is the protective shield, making sure this life flourishes without hiccups. 

    As the lines between our digital and physical worlds continue to blur, understanding and valuing both these processes is paramount. It’s essential to appreciate the dance between SDLC and STLC, regardless of whether you’re a budding developer, a business leader, or an everyday user.

    Frequently Asked Questions

    1. Can you have SDLC without STLC?

    While technically possible, it’s not recommended. That’s like building a car without testing its safety. STLC ensures software quality post-development.

    2. Do developers need to know about STLC?

    Absolutely! Knowing STLC helps developers understand potential testing scenarios and can improve the development process.

    3. Why is STLC crucial in modern software development?

    In today’s digital age, user expectations are high. STLC ensures software meets these expectations by identifying and fixing issues before they reach the end user.

    4. Is there a specific sequence for SDLC and STLC?

    Typically, SDLC phases come first, with STLC processes embedded within, ensuring quality checks as the software progresses.

    Rahnuma Tasnim

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