🌊Waterfall

The Waterfall Model was the first software development life cycle (SDLC) model introduced. It is also known as a linear-sequential model where each phase must be completed before moving to the next phase.

Waterfall Model Phases

Phase	👥 Involved	📜 Rules	💡 Notes
Requirements Gathering and Analysis	👨‍💻 Developers, 👩‍💼 Product Manager	Document all requirements in specification	📝 Capture full requirements early
System Design	👨‍💻 Architects	Design system architecture and requirements	📐 High-level technical design
Implementation	👨‍💻 Developers	Build software in small units	⚙️ Code and unit test each unit
Integration and Testing	👨‍💻 Developers, 👨‍🔬 QA	Integrate units and test system	🧪 Validate before next phase
Deployment	👨‍💻 Operations	Deploy after testing passes	🚀 Release to users
Maintenance	👨‍💻 Developers	Fix issues and release updates	🐞 Support and enhancements

🚰 Pros and Cons

Pros:

• 👍 Simple and easy to understand and use

• 📏 Works well for small projects with defined requirements

• 🗂 Clearly defined stages

• 📋 Well documented

Cons:

• 🚫 No working software until late

• 🔀 Little flexibility to change

• ⚠️ High risk and uncertainty

🌊 Waterfall Variations

Iterative Waterfall - 🔁 Cycles of requirements, design, code, test

V-Model - ✅ Tests planned early

Spiral Model - 🌀 Highly iterative with risk analysis

📆 When to Use Waterfall

Use when:

• 📖 Fixed requirements

• 📏 Product is stable

• 💻 Understood technology

• 👥 Resources available

• ⏱ Short duration

📃 Key Documentation

• 📝 Requirements

• 📐 Design

• 🧪 Test Plans

• 📖 User Manuals

🚿 vs 🐣 Waterfall vs Agile

• 🔀 Waterfall is linear, Agile is iterative

• 📏 Waterfall - rigid phases, Agile - flexible

• 👍 Agile allows changes, Waterfall is locked