The Spiral model of software development was developed in 1986 to address some of the problems with the waterfall model. The waterfall model pushes most of the risk to the end of the development period because all the testing of the software is scheduled at the end of the project. The Spiral model reduces risk early by breaking down the project into smaller iterations with each iteration similar to a complete mini waterfall cycle. This causes part of the testing and design to occur earlier in the project, which in turn allows you more time to fix problems as they are discovered. This increases the probability that either the project will succeed or you will realize early that you cannot complete the project successfully within the allocated time and budget. How do you do this? We recommend you use the iterative or spiral software development method rather than the linear waterfall method, or even better use the RUP software development method which is just a version of the spiral development model.
Typically each iteration adds to the work done in previous iterations. This software development method is named spiral because the following steps are repeated over and over in a circle until the project has been completed.
