SDLC is a process that creates a structure of development of software. There are different phases within SDLC, and each phase has its various activities. It makes the development team able to design, create, and deliver a high-quality product.

SDLC describes various phases of software development and the order of execution of phases. Each phase requires deliverable from the previous phase in a life cycle of software development. Requirements are translated into design, design into development and development into testing; after testing, it is given to the client.

Let's see all the phases in detail:

Different phases of the software development cycle

Software Development Life Cycle

  • Requirement Phase
  • Design Phase
  • Build /Development Phase
  • Testing Phase
  • Deployment/ Deliver Phase
  • Maintenance

1. Requirement Phase

This is the most crucial phase of the software development life cycle for the developing team as well as for the project manager. During this phase, the client states requirements, specifications, expectations, and any other special requirement related to the product or software. All these are gathered by the business manager or project manager or analyst of the service providing company.

The requirement includes how the product will be used and who will use the product to determine the load of operations. All information gathered from this phase is critical to developing the product as per the customer requirements.

2. Design Phase

The design phase includes a detailed analysis of new software according to the requirement phase. This is the high priority phase in the development life cycle of a system because the logical designing of the system is converted into physical designing. The output of the requirement phase is a collection of things that are required, and the design phase gives the way to accomplish these requirements. The decision of all required essential tools such as programming language like Java, .NET, PHP, a database like Oracle, MySQL, a combination of hardware and software to provide a platform on which software can run without any problem is taken in this phase.

There are several techniques and tools, such as data flow diagrams, flowcharts, decision tables, and decision trees, Data dictionary, and the structured dictionary are used for describing the system design.

3. Build /Development Phase

After the successful completion of the requirement and design phase, the next step is to implement the design into the development of a software system. In this phase, work is divided into small units, and coding starts by the team of developers according to the design discussed in the previous phase and according to the requirements of the client discussed in requirement phase to produce the desired result.

Front-end developers develop easy and attractive GUI and necessary interfaces to interact with back-end operations and back-end developers do back-end coding according to the required operations. All is done according to the procedure and guidelines demonstrated by the project manager.

Since this is the coding phase, it takes the longest time and more focused approach for the developer in the software development life cycle.

4. Testing Phase

Testing is the last step of completing a software system. In this phase, after getting the developed GUI and back-end combination, it is tested against the requirements stated in the requirement phase. Testing determines whether the software is actually giving the result as per the requirements addressed in the requirement phase or not. The Development team makes a test plan to start the test. This test plan includes all types of essential testing such as integration testing, unit testing, acceptance testing, and system testing. Non-functional testing is also done in this phase.

If there are any defects in the software or it is not working as per expectations, then the testing team gives information to the development team in detail about the issue. If it is a valid defect or worth to sort out, it will be fixed, and the development team replaces it with the new one, and it also needs to be verified.

5. Deployment/ Deliver Phase

When software testing is completed with a satisfying result, and there are no remaining issues in the working of the software, it is delivered to the customer for their use.

As soon as customers receive the product, they are recommended first to do the beta testing. In beta testing, customer can require any changes which are not present in the software but mentioned in the requirement document or any other GUI changes to make it more user-friendly. Besides this, if any type of defect is encountered while a customer using the software; it will be informed to the development team of that particular software to sort out the problem. If it is a severe issue, then the development team solves it in a short time; otherwise, if it is less severe, then it will wait for the next version.

After the solution of all types of bugs and changes, the software finally deployed to the end-user.

6. Maintenance

The maintenance phase is the last and long-lasting phase of SDLC because it is the process which continues until the software's life cycle comes to an end. When a customer starts using software, then actual problems start to occur, and at that time there's a need to solve these problems. This phase also includes making changes in hardware and software to maintain its operational effectiveness like to improve its performance, enhance security features and according to customer's requirements with upcoming time. This process to take care of product time to time is called maintenance.

"So, all these are six phases of software development life cycle (SDLC) under which the process of development of software takes place. All are compulsory phases without any one of the development cannot be possible because development continues for the lifetime of software with maintenance phase".

Software Development Life Cycle (SDL

  • Waterfall model
  • Spiral model
  • Verification and validation model
  • Prototype model
  • Hybrid model
Software Development Life Cycle

Waterfall Model

It is the first sequential-linear model because the output of the one stage is the input of the next stage. It is simple and easy to understand, which is used for a small project. The various phases of the waterfall model are as follows:

  • Requirement analysis
  • Feasibility study
  • Design
  • Coding
  • Testing
  • Installation
  • Maintenance

For information about the waterfall model, refers to the below link:

Spiral Model

It is the best suites model for a medium level project. It is also called the Cyclic and Iteration model. Whenever the modules are dependent on each other, we go for this model. And here, we develop application model wise and then handed over to the customer. The different stages of the spiral model are as follows:

  • Requirement collection
  • Design
  • Coding
  • Testing

For information about the spiral model, refers to the below link:

Prototype Model

From the time when customer rejection was more in the earlier model, we go for this model as customer rejection is less. And also, it allows us to prepare a sample (prototype) in the early stage of the process, which we can show to the client and get their approval and start working on the original project. This model refers to the action of creating the prototype of the application.

For information about the prototype model, refers to the below link:

Verification & Validation Model

It is an extended version of the waterfall model. It will implement in two phases wherein the first phase, we will perform the verification process, and when the application is ready, we will perform the validation process. In this model, the implementation happens in the V shape, which means that the verification process done under downward flow and the validation process complete in the upward flow.

For information about the Verification and validation model, refers to the below link:

Hybrid Model

The hybrid model is used when we need to acquire the properties of two models in the single model. This model is suitable for small, medium, and large projects because it is easy to apply, understand.

C) Models

The software development models are those several process or approaches which are being selected for the development of project based on the project's objectives. To accomplish various purposes, we have many development life cycle models. And these models identify the multiple phases of the process. Picking up the correct model for developing the software application is very important because it will explain the what, where, and when of our planned testing.

Here, are various software development models or methodologies:

The combination of the two models could be as follows:

  • V and prototype
  • Spiral and Prototype