State the working of spiral model
In spiral model, after every phase a review is performed regarding all products developed up to that point and plans are developed for the subsequent cycle. This model is a realistic approach to development of large scale software. It proposes a systematic approach according to classical life cycle though incorporates it into iterative framework. It provides a direct consideration to technical risks. So for high risk projects, this model is very useful. Risk analysis and validation steps eliminate errors in early stages of development.