SDLC vs STLC : What is the difference?

Software development is a very simple process that starts from system planning to its deployment. This simple process turns out to be a bit complicated when the developers have to create enterprise-level software solutions and not small products. And the reason behind it is that software development for complex systems requires a proper methodology and QA services. This is why the concepts like Software Development Life Cycle and Software Testing Life Cycle have come into the picture. But if we compare SDLC vs STLC, these two approaches are interrelated to each other in some way. 

Both SDLC and STLC are used by software development companies when it comes to creating a product for a specific purpose. But they both differ in some or the other way. In this blog, we will understand both of these concepts and have a look at the difference between SDLC and STLC.


1. What is SDLC (Software Development Life Cycle)?

SDLC (Software Development Life Cycle) is a process of activities that every software development company follows in order to create working software. This software development process follows proper steps which include planning, requirement analysis & gathering, software designing, implementation of designs & new approaches, testing, deployment, and maintenance.

This means that if any software development team wants to cover the entire life cycle, it will have to start from the conception of the software and its requirements. Besides, the SDLC life cycle consists of different phases which come with their own processes and deliverables. SDLC makes sure that the apps are developed in a systematic and well-defined manner. This helps the software developers to get a perfect end result and meet the customer’s expectations.

1.1 SDLC Phases

  • Requirements Gathering
  • Analysis Phase
  • Design the software
  • Development
  • Testing
  • Deployment & Maintenance

1.2 Key Features of SDLC

Some of the key features of SDLC are –

  • It comes with detailed documentation of the functions, model structure, and test environment.
  • SDLC offers an efficient risk management concept that can be utilized by software developers to reduce their exposure to risk.
  • It provides step-by-step software development and testing which helps in completing the project before the deadline.
  • With SDLC, the developers, designers, project managers, and business analysts get a clear understanding of their roles and responsibilities in the project.
  • It is a cost-effective process.

1.3 Why SDLC?

Here are the reasons that show why one must choose SDLC in software development-

  • The aim of SDLC is to deliver high-quality software applications as per the client’s expectations.
  • This process ensures that all the stakeholders are aware of the project and its planning.
  • Each phase of SDLC is followed by a formal review which helps in optimum management control.
  • It helps you to create considerable system documentation.
  • In every stage, including the testing phase, there are entry criteria and exit criteria, development stages, and specific deliverables.
  • It offers management plan overhead and lowers project risk.
  • Enables an efficient and faster software development process.

2. What is STLC (Software Testing Life Cycle)?

STLC (Software Testing Life Cycle) is a process that consists of various activities that ensure that the software’s quality is up-to-the-mark. This is a part of the software testing process. The software testing life cycle process is performed by the testing team which ensures the quality of the applications.

Basically, STLC ensures that each new release rolls out smoothly and successfully. It is known as an important and integral part of the SDLC. But it only applies at the time of test phases. The stages of STLC may be repeated multiple times while the project is getting developed before it goes into the software deployment phase. Besides this, an analysis is conducted of all the different tests in the STLC process and it is documented. This is known as a test closure.

2.1 STLC Phases

  • Requirement Analysis
  • Test Planning
  • Test Development
  • Test Environment Setup
  • Test Execution
  • Test Closure

2.2 Key Features of STLC

Some of the key features of STLC are –

  • It determines the system testing type and method.
  • STLC analyzes the system requirements that the software development team gathered from clients and stakeholders.
  • STLC process helps in developing a traceability matrix.
  • Helps in prioritizing the software feature that needs to be tested the most.
  • Describes the test environment setup.
  • Assesses automation feasibility.

2.3 Why STLC?

Here are the reasons that show why one must choose STLC in software development-

  • STLC helps various testing teams to carry out quality improvement activities in different ways.
  • It is easy to understand and implement regardless of its development phase and testing processes.
  • In STLC, the execution phase develops a high-quality software release.
  • Here tests are conducted on each module of the software before the closure of successful software development.
  • It helps in improving the efficiency, and consistency of the software testing process.
  • Software testing life cycle helps in improving the quality of the software development.
  • It helps in removing the flaws of the software at the early stage.
  • STLC assures that clients and end-users of the product receive the best results.
  • It helps in optimizing the quality control in the entire SDLC process

3. Difference Between SDLC and STLC

Let’s have a look at the difference between SDLC vs STLC –

DefinitionSoftware Development Life Cycle is a process that mainly focuses on developing software that can meet the client’s expectations and work efficiently in the technological infrastructure. Besides, it is a cost-effective process.Software Testing Life Cycle specifies what type of test activities must be carried out and when should the testing team accomplish those test activities.
RelationshipSDLC is taken as the predecessor.STLC is taken as the successor.
FocusThe focus of SDLC is on both complete software development and the testing process.The focus of STLC is only on the testing process.
PhasesThe SDLC phases are Requirement Gathering, System Analysis, Software Designing, Coding, Software Test Execution, and Deployment & maintenance.The STLC phases are Requirement Analysis, Test Planning, Designing of Test, Environment Setup, Software Test Execution, and Test Cycle Closure.
Requirement Analysis PhaseIn SDLC, the business analyst collects all the requirements and creates a software development plan.In STLC, the QA team analyses requirements and creates a perfect system test plan.
Design PhaseThe SDLC team creates the high and low-level designs as per the project’s requirements.The test lead or test architect  creates the test strategy.
Coding PhaseIn the coding phase, the software developers create actual code.The STLC testing team prepares for the test environment setup and executes test cases.
Testing PhaseHere the actual testing process starts which includes testing types like Unit testing, Integration testing, Regression testing, performance testing, etc.Actual testing in this phase starts with defect reporting & retesting is done here.
Deployment or Maintenance PhaseIn this last SDLC stage, the development team offers support and release updates.The QA team executes regression suites to check the deployment of maintenance code.
OutcomeThe outcome of SDLC is that users can get a high quality software system.The outcome of STLC is that the users can get bug-free software.

4. Conclusion

As seen in this blog, both SDLC and STLC are the two most important tools for software development while creating a perfectly secured system. SDLC is a system that offers a structured and phased approach while STLC validates the projects for their reliability, performance, and functionality. Besides, both of these tools are known as the top platforms that serve as a framework for software creation and testing.

Itesh Sharma

Itesh Sharma is core member of Sales Department at TatvaSoft. He has got more than 6 years of experience in handling the task related to Customer Management and Project Management. Apart from his profession he also has keen interest in sharing the insight on different methodologies of software development.


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