Waterfall model

The Waterfall model is classical approach to solving engineering problems (most commonly known as an approach to software engineering). It employs a sequential series of activity phases culminating in a single release milestone.

In a typical life cycle following the waterfall model is:

• Requirements collection and analysis
• Software Architecture - design analysis and development
• Preliminary code development and in-house unit testing
• Release candidate code development (culminating in a "feature complete" internal release)
• Alpha Phase: System level and integration testing
• Beta phase: Qualified external users test the pre-release software
• Public Release
• Maintenance / "bug" fixes