1.2 Software Development Methodology: Waterfall Model and Agile Methodology

Software Development Methodology is the organized way of developing software. It is like a roadmap or guideline that tells us how to start, how to move forward, and how to complete a software project step by step. The main purpose of using a methodology is to save time, reduce errors, and make sure the final software meets the needs of the users.

In our Class 11 PECTAA syllabus (Chapter 1), we mainly study two important methodologies: the Waterfall Model and the Agile Methodology. Both are widely used in the software industry, but they are different in their structure, speed, and flexibility.


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Waterfall Model

The Waterfall Model is one of the earliest and simplest models of software development. It is called “waterfall” because, just like water flows downward step by step, the development process also flows downward in fixed steps.

The steps of the Waterfall Model are:

1. Requirement Analysis – First, all the requirements of the software are collected from the user.


2. System Design – A proper plan and design of the system is created based on the requirements.


3. Implementation (Coding) – Programmers write the actual code of the software.


4. Testing – The developed software is tested to find and remove errors.


5. Deployment – The software is installed and delivered to the user.


6. Maintenance – Errors are fixed, and updates are made after the software is delivered.



✅ Advantages of Waterfall Model:

Easy to understand and simple to manage.

Each step is clear and well-documented.

Works well for small projects where requirements do not change.


❌ Disadvantages:

Very rigid, no changes can be made once a step is completed.

If requirements change in the middle, the whole process may need to start again.

Testing comes very late, so errors may be costly to fix.


The Waterfall Model is mostly suitable for projects where requirements are very clear and fixed from the start.


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Agile Methodology

The Agile Methodology is a modern way of software development. It was introduced to overcome the problems of the Waterfall Model. Agile is flexible and iterative, meaning the software is built in small parts called sprints. Each sprint usually takes 2 to 4 weeks, and at the end of every sprint, a working part of the software is shown to the customer.

In Agile:

Work is divided into small cycles (sprints).

Customer feedback is taken regularly.

Changes can be made at any stage.

A working version of the software is delivered quickly.


✅ Advantages of Agile:

Very flexible, changes can be easily made.

Customer is satisfied because feedback is taken regularly.

Errors are found early because testing is continuous.

Faster delivery of working software.


❌ Disadvantages:

Requires experienced developers.

Less documentation compared to Waterfall.

Sometimes difficult to manage for large teams without discipline.


Agile is best suited for projects where requirements change frequently or where customer involvement is high.


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Comparison of Waterfall and Agile

Feature Waterfall Model Agile Methodology

Approach Linear, step by step Iterative, divided into sprints
Flexibility Very rigid, changes not allowed Highly flexible, changes allowed anytime
Customer Involvement Only at the start and end Continuous throughout the project
Testing Done after coding Done in every sprint
Best For Small projects with fixed requirements Projects with changing requirements



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Conclusion

Both Waterfall Model and Agile Methodology are important in the history of software development. The Waterfall Model is simple and structured, but not flexible. Agile Methodology is modern, flexible, and faster, but requires teamwork and experience. By studying both models, students can understand how software projects are planned and developed, and why different models are chosen for different types of projects.