SDLC waterfall model has defined its phases as, system planning, system analysis

(requirement gathering), system design (defining the overall system architecture), system

implementation (coding), system security and support(testing and maintenance). In a this

model, each phase must be completed before the next phase can begin and there is no

overlapping in the phases. In other word it is a linear sequential life cycle model. This model

is important as the Barry Boehm the creator of the model stated that it assists businesses in

managing risks.