Waterfall Versus Agile

Waterfall methodologies offer a more traditional approach. Waterfall is often used in projects where many aspects can be planned up front with relatively little risk. This allows for the project manager to implement a linear approach known as a Linear Sequential Life Cycle Model. In this approach, the project is split up into distinct phases with each phase being reviewed before proceeding to the next phase.  The sequential phases include:

• Gather requirements and document them
• Design
• Implement
• Test
• Deploy 

Agile methodologies are a flexible non-linear continuous iteration of development and testing. This method is often used in software development where up front planning can lead to higher risk.

With an Agile approach, development and testing happen concurrently and there are multiple phases of this, each building upon the previous iterative phase. Agile methods focus on smaller components, building on them over time to develop the final product. The client is involved in each iteration to see the product developed and enhanced over time. 

The illustration below shows Waterfall as a series of steps, each taking place upon completion of the previous step. It depicts Agile as a continuous series of circles repeating the steps (often called ‘Sprints’) over and over again, building on the product over time until completion.