Waterfall model with advantages disadvantages, feature, with diagram

Waterfall model with advantages disadvantages feature, with diagram

Definition:

The Waterfall Model is one of the oldest and simplest models of the Software Development Life Cycle (SDLC). In this model, each phase is completed one after the other in a linear and step-by-step manner, like water flowing down a waterfall.

You can’t go back to a previous phase once it is completed. So, each step must be finished before moving to the next.

Phases of the Waterfall Model:

1. Requirement Gathering – Understanding what the user needs.

2. System Design – Planning the structure and design of the software.

3. Implementation (Coding) – Writing the actual program.

4. Testing – Checking for bugs and errors.

5. Deployment – Releasing the software to users.

6. Maintenance – Fixing problems and updating software after release.

Objectives of the Waterfall Model:

• To complete the software in a structured and step-by-step way.

• To clearly define each phase of development.

• To finish one phase fully before moving to the next.

• To create well-documented software.

Features of the Waterfall Model:

1. Linear Sequence: All steps follow in order.

2. Rigid Structure: Cannot go back to a previous step.

3. High Documentation: Each phase has complete documents.

4. Clear Milestones: When one phase ends, the next begins.

5. Best for Short-Term Projects: Works well if the project is small and requirements are clear.

Advantages of Waterfall Model:

• Simple and easy to use.

• Well-structured and easy to manage.

• Good for projects with fixed and clear requirements.

• Phases do not overlap — easy to measure progress.

• Each stage is well-documented.

Disadvantages of Waterfall Model:

• Not flexible — you can’t go back to change something.

• Not suitable for long or complex projects.

• High risk if requirements change mid-project.

• Late testing may delay detection of serious bugs.

• No working software is available until the end.

Phases of the Waterfall Model (Step-by-Step with Details)

 

1. Requirement Gathering

What Happens in This Phase:

• The client or user explains what they want the software to do.

• Developers collect all needs and write them in a document called the Software Requirement Specification (SRS).

• This includes: features, goals, user expectations, and system behavior.

Goal: Understand exactly what the user needs — because once this phase is done, changes are not allowed.

2. System Design

What Happens in This Phase:

• Based on the requirements, the software design is prepared.

• The design includes:

  • Architecture of the system.

  • Database design.

  • User interface design (what it will look like).

  • Data flow diagrams and technical plans.

Goal: Make a complete blueprint of how the software will work.

3. Implementation (Coding)

What Happens in This Phase:

• Programmers start writing code based on the system design.

• Each part (called a module) is built separately and then combined.

• Developers follow the programming languages and tools decided in the design phase.

Goal: Convert the design into a real working program.

4. Testing

What Happens in This Phase:

• The entire software is tested to check:

  • If it works correctly (called functional testing).

  • If it is fast and safe (called non-functional testing).

  • If there are bugs or errors.

Goal: Make sure the software is error-free and reliable before it goes to the user.

5. Deployment

What Happens in This Phase:

• After successful testing, the software is installed on the user’s system.

• It is now available for real users to use.

• Sometimes, the team gives training or manuals.

Goal: Deliver the final software to the customer.

6. Maintenance

What Happens in This Phase:

• After release, if users face problems or ask for updates, developers fix issues.

• This includes:

  • Bug fixing.

  • Improving performance.

  • Adding new features.

Goal: Keep the software updated and working smoothly for a long time.

Best Case to Use the Waterfall Model:

• When requirements are clear, fixed, and well-understood.

• When the project is short-term and simple.

• When the technology is well-known and there’s no expected change.

• Examples:

  • Small internal tools.

  • College or academic projects.

  • Government or defense contracts with strict requirements