The Spiral Life Cycle is a blending of the traditional waterfall approach with a more evolutionary or incremental approach. A major focus of this approach is that before any work is done in a phase, a risk analysis and a cost/benefit analysis are done. This strategy is depicted in the diagram below.

• Each circuit of the spiral is called a round.
  
• Each round passes through four quadrants (Planning: specify objectives/ alternatives/constraints; Risk Analysis: evaluate and address alternatives and risks; Engineering: develop next level product; and  Evaluation: assess results and plan for the next stage).
  
• Every circuit around the spiral requires development that can be accomplished using the waterfall approach.
  
• Any round culminates in a review followed by a decision as to whether to continue to the next round or rework portions of the current stage process.
  
• Round 0 may be included which examines the feasibility of the project.
  
• The next step is based on which risks are still not fully addressed.  It may involve prototyping to address user interface or system performance risks or the waterfall approach to address program development risks.