The waterfall model is the most common methodology to use in large organizations, but it is not always the best. The waterfall model works best for small projects that are straightforward, have a predictable outcome, are independent, and have low risk. Each phase is completed in a linear sequential development. If work is done out of order then costs and results can significantly very.
Typical phases include Requirements, Design, Construction, Test, Deliver, Operations and maintenance, and Retire. While these phases are similar across various industries, depending on the organization, they may be called something slightly different, combine or expand phases.