In 1975, when Fred Brooks wrote The Mythical Man-Month, most large software projects were organized and managed using a process we now call the waterfall process or model.

The waterfall process was an evolutionary starting point for most of the software process models used today. The more modern software process models can be understood as attempts to overcome shortcomings of the waterfall process, and many things that distinguish current process models are rooted in the variety of ways they attempt to solve those shortcomings.