SDLC (Software Development Life Cycle) methodologies are structured frameworks used to plan, design, build, test, and maintain software.
It breaks down the complex process into distinct phases, providing a framework that helps manage time, resources, and risks throughout the development of a software product.
Types of SDLC Methodologies or SDLC Models
1️⃣ Waterfall Model
A linear and sequential development model where each phase must be completed before moving to the next.
Key Features:
- Requirements → Design → Development → Testing → Deployment → Maintenance
- No going back to previous phases
- Best for projects with clear, fixed requirements
Used In:
Government, manufacturing, construction, highly controlled environments.
2️⃣ Iterative Model
The product is built step-by-step in small cycles, with feedback after each iteration.
Key Features:
- Build → Test → Improve → Repeat
- Each version is better than the previous
- Reduces risk early
- Good when complete requirements are not known initially
Used In:
Prototyping, early-stage product development, systems requiring gradual evolution.
3️⃣ Spiral Model
A risk-driven software development model combining Waterfall + Iterative + Risk Management.
Key Features:
- Each spiral = Planning → Risk Analysis → Engineering → Evaluation
- Focuses on risk reduction
- Excellent for large, complex, high-risk projects
Used In:
Defense, aerospace, expensive systems where failure is costly.
4️⃣ V-Model (Verification & Validation Model)
A “V-shaped” model where testing activities happen in parallel with development phases.
Key Features:
- Each development phase has a corresponding testing phase
- Very structured and strict
- Great for systems requiring validation & compliance
Used In:
Healthcare, automotive, safety-critical software, regulated industries.
5️⃣ Big Bang Model
Little to no planning — development starts immediately and evolves as needed.
Key Features:
- No formal process
- Suitable only for small, experimental, or short projects
- Very high risk and unpredictable
Used In:
POCs, experiments, small teams building quick concepts.
6️⃣ Agile Model
An adaptive, flexible, iterative model where development happens in small increments (Sprints).
Key Features:
- Continuous improvement
- Responding to change over following a strict plan
- Customer involvement at every step
- Works in Sprints (Scrum) or flows (Kanban)
Used In:
Modern software development, ecommerce, SaaS, mobile apps, startups.
📌 Are these the only SDLC models?
No — but they are the most standard and widely used models.
Other recognized SDLC approaches include:
- Incremental Model
- Prototype Model
- RAD (Rapid Application Development) Model
- DevOps Model
- Hybrid Model (Agile + Waterfall)
- Scrum Framework (under Agile)
- Kanban (under Agile)
But the core SDLC models (commonly taught and used) are exactly the ones you included.