ABSTRACT
Executive summary: This method is the second oldest method after cowboy. It originated in the late 1960s when software projects grew large enough to require teams and therefore became cumbersome. A similar earlier method was defined in 1956 for use on the Semi-Automatic Ground Environment (SAGE) defense system. Historically, waterfall development was used on more than 2,000,000 projects between about 1970 and 2014, including some major applications that are still in use. Waterfall is still widely used, although many other methods such as Agile, team software process (TSP), and Rational Unified Process (RUP) have supplanted waterfall. The quality and productivity results of waterfall are not as good as the better replacement methods.
