What is a Software Development Life Cycle? Phases and Models of SDLC Explained

The Software Development Life Cycle (SDLC) is a methodology we follow to create high-quality software. It is widely popular in the software industry as it enables software developers to build, design, and develop high-quality software products. It focuses on creating software products that meet or exceed the customers’ expectations. 

Why do we use SDLC? How does an SDLC process work? The following article will answer these questions by giving you a detailed overview of the software development life cycle. 

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What is a Software Development Life Cycle?

SDLC, the acronym for Software Development Life Cycle, is also called Software Development Process. It is a framework that defines the tasks a team must perform at every step in the software development process. The international standard for SDLC processes is ISO/IEC 12207. It aims to be the standard defining all the necessary tasks for developing and maintaining software. 

SDLC consists of an articulated plan that describes how to develop, maintain, replace or enhance particular software. The life cycle of a software product defines a methodology to improve its quality and the overall development process. 

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SDLC aims to produce software with the highest quality at the lowest cost in the shortest time possible. It gives a well-structured flow of phases an organisation can use to create high-quality, well-tested, and ready for production software. 

What are SDLC Models?

Software development life cycle models in Software Engineering guide the development process. The different SDLC models are: 

Waterfall model

The Waterfall model was the first software development life cycle model and remained the most popular model. 

Agile model

The Agile model is an iterative and incremental software development life cycle model, where the requirement analysis, design, and development phases take place in iterations called sprints.

Spiral model

The Spiral Model is a software life cycle model that combines some aspects of the Waterfall Model and the iterative and incremental nature of the Agile Model. The risk-driven model involves constant evaluation and risk analysis throughout the project life cycle.

The SDLC models in software engineering incorporate several designs, each with its own strategy and aptitudes. The most commonly used versions in software development are Waterfall, Agile, and Prototyping – all of which have their separate benefits and shortcomings, with builders able to opt for whichever model best fits their necessities.  

Tasks advance through successive steps for the traditional Waterfall version, from the mustering of requirements to implementation. On the other hand, Agile furnishes an iterative plan emphasizing collaboration, suppleness, and attentiveness and includes sprints during all phases, such as designing, coding, testing, and executing. Regarding Prototyping, this pattern underscores the formation of prototypes before formulating a concluding product, offering a method to test the software prior to the dedication to it – mostly applicable for less complicated projects. 

SDLC Stages

Despite the approach applied, multiple stages are required within the software life cycle models. These consist of:    

1. Analyze – the opening phase which involves garnering and assessing the commercial requirements to identify what the software should perform, what characteristics it should include, and constraints that should be considered throughout the design procedure.   
2. Design – during this stage, developers create software structure, layout specifications and interface configurations in order to visualize how the program will work. 
3. Develop – involving coding, assessment, sustaining source code, and delivering the final result. 
4. Testing – exercising the software to guarantee functionality and meeting anticipations. 
5. Finalize – ultimately bringing the software to a live production environment requiring sub-stages like fitting, configuring, instructing, and user acknowledgment trial. 

Therefore, the SDLC is a process enabling organizations to maintain software responsibly. Its usage is dependent on distinct business desires and job targets. In any case, understanding the fundamental role of every step in manufacturing constantly high-quality software is an essential factor for any development team.

SDLC Process Models 

You can use software development life cycle models (also called Software Development Process Models) for software development. Every process model has a specific sequence of steps according to its type to offer the best results. The most popular SLDC processes are: 

• Big Bang model
• V-model
• Spiral model
• Iterative model
• Waterfall model

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Other relevant methodologies include Rapid Action Development and Prototyping models, RAD model, and Agile model. 

Why is SDLC important?

The software development life cycle is vital for the development of any software system. It gives a framework for a standard set of deliverables and activities and is a mechanism for tracking and controlling the project. 

SDLC makes project planning visible to all involved stakeholders of the development process. It allows you to reduce project risk and project management plan overhead. SDLC enhances client relations and improves the development speed, making the entire process highly efficient. 

What are the different phases of a Software Development Life Cycle?

You can divide the SDLC process into the following phases: 

1. Requirement Analysis
2. Feasibility Study
3. Design
4. Coding
5. Testing
6. Deployment
7. Maintenance

Let’s look at each of these phases in detail: 

1. Requirement Analysis 

In the first phase of a software development life cycle, you aim to identify the current problems. This includes getting input from customers, industry experts, salespeople, programmers, and all the stakeholders. In this stage, you gather information about the strengths and weaknesses of the existing system to determine how you will improve the same. 

Usually, the senior members of the team complete this phase. This phase aims to get a clear picture of the project’s scope, issues, opportunities and directives that started the project. 

You’ll need to get detailed information about the project’s requirements to finalise the timeline for the project. Once you have gathered all the necessary data about the existing system, your project goal, and its requirements, you can start working on the next phase. 

2. Feasibility study

In the feasibility study, you have to define and document the software requirements for which you will need to create the ‘Software Requirement Specification’ document or SRS, in short. Feasibility checks are of five types legal, technical, economic, schedule, and operation feasibility. 

You must consider each of the five types of feasibility studies during this stage as they all help you understand the feasibility of your project. 

For example, the legal check would help you determine if you can handle the project with other regulatory compliances or frameworks. Similarly, the economic assessment would tell you if you can complete the project within the available budget. 

Read: Top 20 Software Development Project Ideas

3. Design

Here, you have to prepare the system and software design documents to define the system architecture. It serves as input for the upcoming phase of the SDLC process. You’d create two kinds of design documents: 

• High-level Design (HLD)
• Low-level Design (LLD)

The HLD lists out the outline about the functionalities, description, and dependencies between the modules, whereas the LLD focuses on listing error messages, complete information about the interface, database tables, functional logic, and related areas.