What is the software development life cycle?

The software development life cycle is a process for designing, developing and testing high-quality software. To land your first software engineering job, you’ll need to be able to describe the seven stages of SDLC. Hiring managers tell us that a crucial skill most new grads lack is production. Familiarity with SDLC will prepare you to hit the ground running when you start working as a software engineer — especially if you’re hired at a startup.  

The software development life cycle model guides developers to create software that meets customer expectations and is completed within specific time and cost constraints. The most common type of SDLC is the ‘waterfall’ model, where the outcome of each phase acts as input for the next phase.

Stage 1: Planning

The first stage is the most important in the software development life cycle. Here, you’ll assess the strengths and weaknesses of the current system with the goal of improving it. If you’re developing a new product, you’ll analyze the pros and cons of competitors and work to identify a gap in the market. 

This stage involves getting input from all stakeholders, including customers, salespeople, industry experts and programmers. It’s designed to give everyone involved a clearer picture of the scope of the project as well as anticipated issues, opportunities and directives which triggered the project. 

By the end of this stage, everyone should agree on a business problem to solve and a solution at hand, such as: 

Problem: Existing banking systems don’t assist users with building a savings program

Solution: Design an improved app with a built-in savings feature that prompts users to add money to their savings account on a regular basis

OR

Problem: Adults caring for elderly parents remotely often lack ways of checking in on them 

Solution: Create a new wearable device and associated alert system to enable children and their parents to check in on each other

Stage 2: Defining requirements 

Once everyone agrees on the business problem at hand, the next step is to gather requirements for the project. This helps companies finalize the timeline and costs of software development, while also detailing the risks involved and providing contingency plans to mitigate those risks. 

By the end of this stage, you should have come up with a Software Requirement Specifications document. An SRS specifies the roles and expectations for every team involved in development, from IT to product and marketing. 

The SRS helps to ensure requirements are fulfilled and it can also help you  make decisions about a product’s life cycle — such as when to retire a new feature. 

Stage 3: Designing product architecture

Before the product goes into development, developers must devise a design approach for the software architecture that will undergird the product’s functionality. At this stage, developers propose and document each approach in a Design Document Specification. 

A design approach defines all the architectural modules of the product along with its communication and data flow representation. 

All stakeholders review the DDS and provide feedback/suggestions. It’s crucial for the developer to have a plan for collecting and incorporating stakeholder input into this document. Failure at this stage will almost certainly result in budget overruns at best and total collapse of the project at worst.

Stage 4: Build and Develop the Product

Finally — the production stage! This is where programming code is generated per the DDS and it’s arguably the longest phase of the SDLC. Developers must follow the coding guidelines defined by their organization and programming tools like the defilers, interpreters and debuggers used to generate code. 

Software developers typically use high-level programming languages such as C., C++, Pascal, Java and PHP for coding. In the coding phase, tasks are divided into units or modules and assigned to various developers.

Stage 5: Testing

Once the software is complete, it’s deployed in a testing environment. Testing teams check to see that the software meets the quality standards defined in the SRS and that the entire system is functional. This is done to ensure that the application works according to the customer requirements. 

At this stage, the QA or testing team may find bugs or defects and communicate it to developers. Developers then fix the bug and send it back to QA for a re-test. This back-and-forth continues until the software is bug-free and works according to the business needs of the system. 

Stage 6: Deploy/launch

Once the product has passed testing, it’s ready to be launched formally to the appropriate market. New products tend to be rolled out incrementally and made available to a limited number of beta testers for user acceptance testing. 

Based on this feedback, the product may be released as is in full or with suggested enhancements from the target market. 

Stage 7: Maintenance

When software hits the market, real-world conditions can be very different from the testing environment. Developers may discover bugs from edge cases that weren’t previously tested for, or they might have overestimated server capacity. Also, as market conditions change, developers will need to update and advance the software to keep up. 

Maintenance is a long-term phase of the SDLC that typically involves the following:

  • Fixing bugs
  • Upgrading the application to a newer version to keep up with mobile or computer operating systems
  • Enhancements such as adding new features to retain users or keep up with the competition