What Is a Software Development Life Cycle? : Detailed Guide (Updated 2024)

Software Development is a complicated process and without a systematic approach, the whole thing would be a mess. 

This is where the Software Development Life Cycle (SDLC) comes into play with a structured and systematic approach to developing high-quality software. It involves efficient planning, clear communication, and effective management of resources throughout the development process. 

SDLC helps identify and rectify defects early, reduces development costs, and ensures that the final product meets user requirements and expectations.

Here we will discuss:

• What is a software development life cycle?
• Why is SDLC important?
• Different stages of SDLC
• Different models of SDLC
• Best practices for SDLC

What is a Software Development Life Cycle?

The Software development life cycle (SDLC) is a framework that is used for top-quality software. This framework has grown into what it is today from the early days of software in the 1950s. Before, SDLC was not exactly a commonly used term as software development was not a complicated process.  

With advancements in technology and software becoming more diverse and complicated, a framework of essential activities needed to be established and that is how SDLC became what it is now.

SDLC divides different processes in software development into different phases. These phases make the whole process simple to understand. As a result, developers understand their necessary activities easier and stakeholders understand the status of production better.

Why SDLC is important

SDLC takes into consideration every phase of software, which includes activities before, during, and after development. 

Some key benefits are:

• A standardized work cycle is facilitated with systematic report deliveries
• Project planning, cost estimation, and scheduling are done properly
• Visibility of each stage of the process to stakeholders is increased
• Problems can be tracked down and taken care of easily
• The development process is sped up and downtime decreases
• Risk is lowered and there is less time loss 
• Costs are kept to a minimum
• Resources are allocated properly

Here is another important thing to know about SDLC – security. It used to be a part of the testing phase only; i.e., the stage after development and before launch where bugs and defects are tested.

However, things have changed and different security assurance activities are now followed throughout the whole SDLC, such as penetration testing, code review, architecture analysis, and threat modeling. Some benefits of this are:

• Security is always a concern during development so it keeps an eye on that.
• Stakeholders are aware of measures taken to strengthen security.
• Early detection of errors during the development process.
• Due to early reductions of errors and bugs, they are dealt with right away which saves costs down the line.
• An overall decrease in business risks.

Different stages of SDLC

SDLC categorizes every stage of development in the following ways.

Project planning

Project planning is the first phase of SDLC where we determine most of the important elements to put time and effort into. The main aspects that are discussed in this phase are

• Purpose of application: The purpose will determine so much of the designing stage of the process. Whether it is an application through which people will buy things, or it will be a videogame, the development process will be very different based on that.
• End user details: Who will be the end users will also play a big role. Software made for a tech-savvy audience will be very different than software that is to be used for a general audience. 
• Formats and attributes of application design: Here, you are to determine which language to use for coding and what attributes to implement in the application.
• User interface (UI) and User experience (UX): You are to decide what kind of user interface (UI) you wish to implement and what kind of User experience (UX) you need to create that will be best for the end users. You may also need to decide on design elements to use in the UI that are best for the app.
• Allocating costs and resources: This is where you understand what kinds of costs you will be incurring and make a budget for the project. You also decide what type of resources you will be putting into each phase of the process.

Requirement analysis

Once the planning stages are complete, you will need to understand and document all the necessities. 

Here are some topics discussed here.

• Detailed information on every element of design
• Validating installation
• Calibrating security protocol
• Risk analysis

Once these are determined, the requirements are put through an SRS (Software Requirement Specification).

Design

By following the SRS, the best solutions and specifications are determined.

The software specifications are documented through what is known as a Design Document Specification (DDS). This DDS is presented to analysts and stakeholders for review and approval.

Development

This is the stage where code writing starts. High-level programming languages such as C, C++, Java, Pascal, or PHP are used. The language is chosen during the planning phase based on the type of software being made.

Software products are implemented into the creation process and tools like compilers, interpreters, debuggers, etc are used.

Testing

Here, the software is put through the test in multiple environments to check its functionality. A quality assurance or testing team is present who will check the software for bugs and report them. The dev teams take these reports and make necessary changes.

This process continues until the testing teams decide if the software is stable enough for release.

Deployment and Maintenance

In this stage, the software is released to the target. After launch, you are very likely to meet with a lot of user feedback and criticism. New updates are made to the application to fix newfound issues.

Different models of SDLC

There are many models of SDLC that you can choose to follow. The popular ones are:

Waterfall model

The waterfall model is one of the oldest models of SDLC. The main idea of this model is that it moves forward whenever a stage is completed. Two stages cannot happen simultaneously and they need to happen one after the other.

Pros:

• Simple to implement
• Clear and precise Instructions 

Cons:

• Time-consuming and not suitable for quick delivery
• Not adaptable to changes down the line
• Incredibly specific requirements needed

Who is it best for?

This is best used for software with clear requirements that can take a long time to be developed. Software relating to Customer Relationship Management (CRM), Supply chain management, Inventory management systems, Points of sales, and systems similar to them are usually made using the waterfall method.

Agile model

The agile model is the method of making a small scope but usable software at the start adding on new aspects according to needs and updating the application slowly over time. Multiple versions of the same project are made through this.

It is named agile due to its quick nature of being able to adapt to new situations and requirements. This is currently one of the more commonly adapted models by most software developers. 

Pros: 

• Adaptable to changes
• More feedback from end users 
• Easy to make changes

Cons:

• Needs expert developers 
• Very little documentation and clarity 

Who is it best for?

The agile method is best for creating software that requires quick delivery and end-user feedback early on in the development process to proceed further. It is commonly used for websites and web apps as you can create an initial version to bring people in and update it later down the line to add more features.

DevOps model

The DevOps model is a system that allows the development team and the operations team to work together. Rather than waiting for the other team to finish their work, the downtime is removed by the two teams working with each other.

The DevOps model is represented with an infinity symbol signifying its endless process.

Pros:

• Less downtime is created.
• An overall decrease in costs.

Cons:

• Great communication skills are needed.
• Needs expert developers 

Who is it best for?

If your team has excellent teamwork, the DevOps model would be best for you to take on most software projects.

Lean model

The lean model for software development is based on lean manufacturing practices and principles which emphasize better flow of work and creating a continuous developing culture. The seven lean principles are

• Amplify learning
• Eliminate waste
• Deliver as quickly as possible
• Make decisions with enough time
• Empower your team
• Promote integrity in your team
• Build holistically 

Note: Building holistically means building in sync with every department.

This software development approach focuses more on team building than the product itself.

Pros:

• The benefits of the seven lean principles are seen
• Gradual growth of the developer team

Cons:

• Not suitable for a part-time team
• Time-consuming to set up

Who is it best for?

If you have started a team or a company to take on multiple projects soon, it will be better in the long run to use the lean method. The lean method is a model that focuses on team building rather than the product itself so it will strengthen your team and their capabilities with every project they undergo.

Iterative model

The iterative model focuses on making software in an incomplete but deployable state in a short time but repeatedly making it multiple times. The idea is that repeatedly making it will improve it after learning from the mistakes of previous cycles.

Pros:

• Easily identified problems
• Easy changes
• Easy to understand

Cons:

• Expensive if not controlled properly.
• Very time-consuming.

Who is it best for?

The iterative model is best for tackling larger projects that may need changes down the line and cannot afford to have too many bugs. This approach is common for UI/UX designs and e-commerce websites.

V-shaped model

The name of this model comes from the V-shaped framework it creates. Here, both verification and validation of the different phases occur at the same time. The phases do not proceed if the validation does not occur. 

Pros:

• Easily trackable by developers and stakeholders.
• Very disciplined as problems are taken care of more frequently.

Cons:

• Can be time consuming
• Not suitable for large and complex projects.

Who is it best for?

The V-shaped model is suitable for small projects where well-defined and specific requirements are laid out to developers. It is quite common in safety-related automotive software.

Big Bang model

Compared to other models, Big Bang models are more unorganized and sporadic. Most of the resources are spent in the software development stages. There are no set structures followed and developers have to figure out what they need to do as they go along. 

Pros:

• Best for projects with a tight deadline.
• Very easy to set up.

Cons:

• Not suitable for large and complex projects.
• No documentation or tracking is possible.

Who is it best for?

The Big Bang model is sort of a last-resort model used when faced with a tight deadline. It is mostly used for study and practice projects.

Spiral model

The spiral model is considered to be a mix of the waterfall model and the iterative model. Like the waterfall model, it moves on from one phase to another as each stage’s activities are complete, but whenever a bug or a risk is discovered, it repeats some of the processes to eliminate them. 

Pros:

• Changes can be easily made in this model.
• Really good risk and problem analysis.

Cons:

• Only good for large complex projects.
• Very expensive.

This model emphasizes removing bugs through repetition of the cycle so it is used for software where bugs can be a big issue. This model is popular among video game software developers.

Which model to use?

The model to adopt in your software development project will depend on the type of software you are developing and its purpose. All the models have their unique advantages and disadvantages that appeal to different structures and software. 

The waterfall is the oldest model and is suitable for projects that do not get a lot of customer feedback early on. It is, however, considered outdated as a lot of software is created with open-ended goals these days, so different approaches are taken to keep these goals in mind.

The most commonly used model is the agile model due to its versatility. The agile model lets you create software in a short time and the improvements and updates are based on customer feedback. This can allow you to make software that is more in tune with the needs of the end users.

However, be mindful that just because it is commonly used does not mean it will suit your project right away. Look at the pros and cons to decide which will be better for you.

Best practices for SDLC

Not that you know what a software development life cycle is, let’s talk about the signs of a well-executed SDLC are:

• Quality coding standards
• Great collaboration among teams
• Deployment of a successful security program
• Streamlined workflows 

Some precautions to follow

There are a few traps you need to avoid in your SDLC. It is quite common for developers to steer in different directions while in the development process. While sometimes that can be unavoidable, make sure not to stray too far from customer and stakeholder demand.

Having models that allow early implementation from customer feedback is a blessing. However, it can also be a curse. Focusing too much on customer feedback can take you away from the original intention of the software.

Sometimes, the audience does not know what they want. And the final product that was built on their influence may not be what they wanted. So make sure to plan carefully to avoid such issues.

The SDLC can be a very complex set of rules to follow. Make sure the guidelines and rules are strictly adhered as to not lose focus and derail the whole project into failure.

Wrapping it up

What is a software development life cycle? We hope now you understand what SDLC is and its essential phases. All these phases have various aspects that need to be taken care of, and SDLC comes with different models that are suited for different projects. We hope you got to learn about the different models of SDLC and which ones would be suitable for you.

FAQs

Q. What is the difference between Agile, Lean, and DevOps models?

Ans. The work processes of the Agile, Lean, and DevOps models can seem similar when glanced at. There are a few differences to be mindful of.

The purpose of the Agile model is to make deployable software very early and consider customer feedback to proceed with development.

The lean method focuses on eliminating “waste” and time loss and focusing on the improvement of a team over time to create the most efficient SDLCs.

The DevOps model emphasizes collaboration between the development team and the operations team to eliminate downtime between the two.

Here, “agile” is an approach to quickly deploy a version of software that will be updated post-launch.

Lean is a model focused on the improvement of the developers.

DevOps is a collaborative system between two teams.

So, while the goals of these three models are to ultimately reduce downtime and expedite the life cycle, the approaches are very different from each other.

Q. Can I skip a few phases in the SDLC? 

Ans. As we can see from the Big Bang theory model, you can certainly skip a few phases from the SDLC. However, the Big Bang Theory model is a model used for sudden and rushed projects most of the time. The phases in SDLC are designed to deliver results in software development with very few flaws in them.

Skipping a few seemingly non-essential steps can create a lot of problems that you will not be able to track down and cause a lot of hassle in the long run. So it is highly recommended to not skip phases.