Stepwise refinement is a problem solving technique that underlies many software engineering techniques. It can be defined as a means to:

decompose the problem into pieces of equal importance

postpone decisions on details until as late as possible in order to be able to concentrate on the important issues

review the project's deliverables such as specification documents and code by stepping through them during review meetings

specify the product's design up front in order to minimize integration problems during later phases

feedback to the earlier phases any changes made thus closing the feedback loop fundamental to the waterfall approach