Waterfall

This can be an approach to develop software. It belongs to the oldest software development processes.
The name results from cascading single actions like a waterfall.

There is a modification which allows you to step from one action back to the previous one if you detect some mistakes.

This process is very static and you have to focus mainly on acquiring the requirements because its difficult and expensive to do the whole process again if your customer istn’t satisfied.
(for example: (1): 2 years ; (2): 1 year ; (3): 1/2 year … (6): years)