The Waterfall model has been around for more than 40 years. It was first described in a 1970 paper (Dr Winston W Royce), as one of the very first formal software development process models.
We often describe Waterfall as a ‘linear-sequential lifecycle model’. This means that it follows a simple structure of phases where the results of each phase cascade down to the next level of development. In other words, we’re not so much looking at one big Niagara Falls, but a series of cascading waterfalls – each with their own little pool of activities.